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Journal articlePratomo U, Tsary DH, Rachmadona N, et al., 2026, , Journal of Electroanalytical Chemistry, Vol: 1020, ISSN: 1572-6657
Green hydrogen has established its position as a potential alternative to fossil fuels due to its high energy density, versatility in upgrading chemicals and decarbonizing industrial processes, and zero associated carbon dioxide emissions when used. An emerging method for producing green hydrogen is through photoelectrochemical (PEC) water splitting, where solar energy is used to drive the conversion of water into hydrogen and oxygen. Bismuth vanadate (BiVOâ‚„) has emerged as one of the most promising photoanode materials owing to its visible light active band gap, ease of fabrication, and chemical stability. However, the intrinsically fast recombination of charge carriers and sluggish oxygen evolution reaction (OER) hinder solar energy conversion efficiency for water splitting in this material. While significant progress has been made in developing multi-layered BiVO4-based photoelectrodes to elevate solar-to-chemical conversion efficiency (STC), charge transfer across each interface can be restricted when there is weak electrical and interfacial alignment between layers. To address this issue, researchers are developing ‘bridging materials’ that can rectify charge transport between the layers of such systems; improving interfacial charge transfer, regulate charge transfer directions, enhance catalyst stability, and ultimately increase PEC performance. This review presents recent progress in interface engineering for BiVOâ‚„-based photoelectrochemical systems, emphasizing how bridge materials at key photoelectrode interfaces enhance performance. Intrinsic limitations of BiVOâ‚„ are first outlined, along with strategies to overcome them through rational materials design. The functions of bridge materials in different electrode architectures are then described, including fabrication methods ranging from dry to wet chemical routes. Finally, current challenges and future directions for this emerging approach are discussed.
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Journal articleMesa CA, Selim S, Kafizas A, et al., 2026, , ACS Catalysis, Vol: 16, Pages: 17655-17667
Nanostructuring is established as a photoelectrode performance enhancing route for solar-driven catalytic processes. However, it is often unclear to what extent the increase in photoelectrode physical surface area directly results in a commensurate increase in photoelectrochemically active surface area. While there are established methods for estimating the physical and electrochemically active surface areas, it is challenging to quantify the operando photoelectrochemically active surface area of nanostructured or nanoparticulate photoelectrodes. Herein, we demonstrate that photoinduced absorption (PIA) spectroelectrochemistry can be employed to quantify the operando photoelectrochemically active area of photoanodes for the oxygen evolution reaction (OER) by exploiting the strong dependence of OER turnover frequency on physical surface hole density. We investigate BiVO<inf>4</inf>, α-Fe<inf>2</inf>O<inf>3</inf>, and TiO<inf>2</inf> photoanodes with contrasting morphologies – planar, nanoparticulate, and nanostructured. Our study combines operando measurements of TOF and geometric surface hole density to quantify the photoelectrochemically active surface area of each catalytic system for OER. For the nanostructured photoelectrodes, the photoelectrochemically active surface areas determined from our PIA analyses are shown to be in agreement with their physical surface area, consistent with their good OER performance. This contrasts with the low photoelectrochemically active surface areas compared to their high physical surface area determined by the nanoparticulate photoelectrodes, resulting in poor performance. We conclude by demonstrating how the photoelectrochemically active surface areas of nanoparticulate photoelectrodes increase when driving more kinetically facile reactions or by adding co-catalysts.
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Journal articleLi L, Wang T, Hu B, et al., 2026, , Journal of the American Chemical Society, Vol: 148, Pages: 26322-26332, ISSN: 0002-7863
Photoelectrochemical (PEC) oxidation of biomass-derived organics (e.g., glycerol) can outperform water oxidation while coproducing value-added chemicals. However, the kinetic basis of this enhanced performance, such as hole consumption dynamics and space–charge–layer (SCL) trap filling under PEC operating conditions, remains poorly understood. Using BiVO4 as a model photoanode, we combine operando optical and photocurrent spectroscopies, including trap-selective pump-push photocurrent (PPPC) mapping, to track bulk and interfacial charge-carrier dynamics over the femtosecond-to-second (fs–s) time scale. Overall, we show that glycerol oxidation accelerates interfacial hole consumption, lowering the surface-hole density required to sustain a given photocurrent, thereby suppressing SCL trap filling and trap-mediated recombination. Glycerol increases the per-hole turnover frequency 32-fold (∼3.5 to ∼113.2 s–1) and the photocurrent density at 1.23 VRHE from ∼0.5 to ∼1.3 mA cm–2, while formic acid and dihydroxyacetone are the dominant quantified liquid products. Spatially resolved PPPC mapping (over ∼20 mm2) shows that glycerol also suppresses localized trap-filled hot spots. Glycerol leaves the dominant early time bulk carrier dynamics largely unchanged while suppressing the microsecond buildup of trapped electrons in the SCL. These results highlight microsecond time-scale kinetic competition between interfacial hole consumption and SCL trap filling as a key design principle for PEC oxidation of renewable organics.
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Journal articleCreasey GH, Kafizas A, Hankin A, et al., 2026, , JPhys Energy, Vol: 8, ISSN: 2515-7655
Testing photoelectrochemical (PEC) and photovoltaic devices under realistic operating conditions is a critical phase of system development. However, most studies still focus on standard AM 1.5 G tests at one sun (1000 W m−2) irradiance with direct collimated light beams, which does not capture outdoor operation under broad angular illumination from diffuse skies and low solar elevation. Outdoor field trials are difficult to benchmark reproducibly due to the unpredictable nature of outdoor environments. Herein, we demonstrate a simple, laboratory-based method for generating controlled, angularly broad ‘quasi-diffuse’ illumination by coupling a continuous solar simulator to an integrating sphere. By positioning a PEC device at the integrating sphere exit aperture, we produce a controlled quasi-diffuse illumination geometry and demonstrate its use in two case studies involving WO3|BiVO4|NiFeOOH photoanodes: one with a planar architecture and another coupled with a crossed-compound parabolic concentrator (CCPC) with wide-angle acceptance, designed to harvest diffuse and off-normal light. After normalisation to one-sun equivalent irradiance, the non-concentrating (planar) configuration performed similarly under direct and quasi-diffuse irradiance, whereas the CCPC-coupled configuration retained 26.3% of the direct-illumination photocurrent under quasi-diffuse conditions, consistent with acceptance-angle limited concentration. Whilst demonstrated here for non-concentrating and CCPC-coupled WO3|BiVO4|NiFeOOH photoanodes, this method is in principle extendable to other compact planar photo-absorbers and low concentration non-imaging optics, provided that their dimensions are compatible with the exit aperture of the integrating sphere and their operation remains meaningful at the reduced irradiance available after sphere losses. This work provides a practical, controllable and transferable framework for quasi-diffuse light characterisation that complements
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Journal articleSaeed ZM, Jadhav T, Mathew R, et al., 2026, , Chemical Engineering Journal, Vol: 537, ISSN: 1385-8947
Polystyrene (PS), a widely used commodity plastic, has a persistently low recycling rate, making it a major contributor to plastic pollution. Selective PS upcycling under ambient conditions remains challenging due to its chemically inert structure, characterized by stable Csingle bondC and Csingle bondH bonds. As a consequence, efficient PS degradation typically requires energy-intensive pyrolysis or harsh oxidizing conditions. Existing homogeneous photocatalysts, such as strong acids or metal salts, are unsustainable long-term solutions for PS waste management due to their lack of reusability and complex separation requirements. Although covalent organic frameworks (COFs) and covalent triazine frameworks (CTFs) have previously been explored as general photocatalysts, their use in selective PS upcycling remains underexplored. Here, we report an iron-doped CTF for the efficient photocatalytic upcycling of PS under ambient conditions. By harnessing the framework's porous character and tunable electronic and photophysical properties, the catalyst incorporates less than 3 wt% iron and offers a sustainable alternative to photocatalysts with higher metal content. Synthesized via solvent-free mechanochemical Friedel-Crafts alkylation of trichlorotriazine and phenothiazine, the CTF forms a porous, p-type semiconductor with FeCl4− ions cross-linking 2D CTF polymer sheets to form an [FeCl4]@CTF heterogeneous photocatalyst. The disclosed [FeCl4]@CTF photocatalyst achieves 100% degradation of commercial and post-consumer PS under ambient conditions, yielding approximately 70% of valuable aromatic compounds with high selectivity. The scalable mechanochemical synthesis of the CTF, coupled with its reduced reliance on high metal loadings provides a sustainable blueprint for organocatalyst-driven plastic waste management using earth-abundant metals.
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Journal articleYang G, Huang W, Wang Y, et al., 2026, , Journal of Materials Chemistry A, Vol: 14, Pages: 20548-20557, ISSN: 2050-7488
The scarcity of Ir presents a major challenge for scaling up its use as a water oxidation electrocatalyst in proton exchange membrane (PEM) water electrolysers. Developing conductive and stable supports is an effective way to reduce iridium loading while maintaining performance. However, the influence of support conductivity and stability on Ir-based catalytic activity remains poorly understood. The behaviour of the support is often obscured in conventional membrane electrode assembly (MEA) systems because IrOx itself is both highly conductive and exceptionally stable. To decouple support conductivity and passivation effects from the intrinsic conductivity of IrOx, we demonstrate a screening platform by studying a series of Ti–Nb alloy thin films produced by sputter deposition and investigate their performance as supports for IrOx water oxidation electrocatalysts. A range of electrochemical tests including accelerated stress tests (AST) were carried out on these samples, where characterisation techniques, including X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM), demonstrated the in situ formation of passivation layers on these supports during water oxidation. Our results suggest that a ∼10 nm oxide passivation layer forms on metallic Ti-based supports. On alloying Nb with Ti metal, a more insulating rutile TiO2 phase forms during water oxidation whereas an anatase TiO2, with higher conductivity, is observed on the pure Ti support. Consequently, although alloying Ti with Nb improves the bulk conductivity, the structure of the oxide passivation layer results in a drastic decrease of conductivity and water oxidation activity. Our results demonstrate the importance of the structure and composition of surface oxide phases formed during water oxidation in controlling the overall stability and conductivity of support materials.
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Journal articleEknapakul T, Kadasae N, Kafizas A, et al., 2026, , Journal of Alloys and Compounds, Vol: 1066, ISSN: 0925-8388
Subsurface silver-modified Bi3NbO7 photocatalysts were synthesized via a hydrothermal method to investigate the role of metal spatial distribution in photocatalytic pathways. Integrated structural, physicochemical, spectroscopic and theoretical analyses confirm that Ag is in the subsurface region rather than forming surface nanoparticles or substituting into the Bi3NbO7 lattice, inducing localized distortions without altering the bulk crystal structure or the electronic band structure. Despite these minimal thermodynamic changes, the photocatalytic activities for Rhodamine B degradation and hydrogen evolution vary significantly across samples. Photoelectrochemical and transient absorption spectroscopic studies reveal that the catalytic activities and selectivity are primarily driven by charge carrier kinetics. Specifically, subsurface Ag dispersion modulates the competition between oxidation, governed by hole availability, and reduction, which is sensitive to electron-hole separation efficiency. This study presents a ‘subsurface-mediated kinetic control’ strategy, offering tuneable reaction selectivity through engineering the spatial location of metallic species.
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Journal articleSotelo-Vazquez C, Wilson R, Lee R, et al., 2026, , Inorganic Chemistry Frontiers, Vol: 13, Pages: 3888-3900, ISSN: 2052-1545
The tungsten trioxide/titanium dioxide (WO3/TiO2) heterojunction is archetypical in photocatalysis, with demonstrated synergetic properties despite some controversy around the predominant band model in these systems. The current work is a systematic study that quantified the synergetic contribution of the WO3/TiO2 heterojunction to the enhancement of photocatalytic activity over the contribution of the TiO2 coating in coreshell nanostructures. The films were produced from atomic layer deposition and chemical vapour deposition techniques and their photocatalytic activity was correlated with transient adsorption properties upon TiO2 coating thickness. The study allowed to identify an optimum thickness range within 21–40 nm, showing the greatest contribution of the heterojunction for a TiO2 thickness of 30 nm. The outputs of this research have strong implications to heterojunction materials design for practical applications.
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Journal articleLi Y, Yao L, Li J, et al., 2026, , Chem, ISSN: 2451-9294
Solar-driven oxidative coupling of methane (CH4) offers a sustainable route for synthesizing value-added chemicals beyond petroleum. To address current thermodynamic and selectivity challenges, a photocatalytic system employing nano-gold-decorated GaN nanowires is developed for the efficient conversion of CH4 into ethane (C2H6), using water as a green oxidant. The optimized catalyst delivers a remarkable C2H6 production rate of 112.6 mmol⋅gcat−1⋅h−1 with 94.9% selectivity and a turnover number of 40,824 after 256 h operation. Mechanistic investigations reveal that photogenerated holes trapped at Au sites oxidize H2O into highly active ·OH radicals. These radicals significantly lower the energy barrier for C2H6 formation via an H-exchange mechanism. Ultimately, the synergistic Au/GaN interface inhibits CH4 over-oxidation, showcasing a highly promising, environmentally friendly pathway for solar-to-chemical energy conversion.
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Journal articleAlghamdi F, Zeng H, Boras G, et al., 2026, , Optics Continuum, Vol: 5, Pages: 954-954, ISSN: 2770-0208
We demonstrate that the addition of an intrinsic GaAs shell to form a p-i-n junction with GaAs/GaAs/AlGaAs core/shells nanowire (NW) enhances the photocurrent density by fivefold compared to a conventional p-n junction with GaAs/AlGaAs NW. The GaAs/AlGaAsmaterial system offers distinct advantages due to its strong visible-light absorption, tunable bandstructure, and compatibility with protective and catalytic overlayers, such as TiO2, which can enhance surface stability and charge separation. What we believe to be a novel photocathode structure demonstrates a one-sun photocurrent density of 0.542 mA/cm2 at an applied potential of 0.20V with respect to the reversible hydrogen electrode (RHE). This work demonstratesthe suitability of GaAs/GaAs/AlGaAs p-i-n core/shells NWs for PEC water splitting and their potential for green hydrogen production.
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Journal articleJahangir R, Podjaski F, Alimard P, et al., 2026, , EES Solar, Vol: 2, Pages: 338-350, ISSN: 3033-4063
Organic based semiconductor materials offer emerging and sustainable solutions for solar energy conversion technologies and electronics. However, knowledge of their intrinsic (photo)physical properties is often limited, especially the effect of dielectric properties (εr = ε′) on exciton separation and charge generation at sub-picosecond timescales, which corresponds to THz frequencies. Thus, THz Time Domain Spectroscopy (THz-TDS) is used to directly and accurately extract the complex permittivity (ε = ε′ + iε″) and THz conductivity (σTHz) of organic Carbon Nitrides (CNx) and other polymers and elucidate the influence of environmental humidities. Overall, the THz dielectric response ε′ of CNx surpasses other organic and even glycolated materials, and water. For the ionic and 2D carbon nitride K-PHI, complex permittivity ε was observed to be strongly humidity dependent, with both ε′ and σTHz doubling from dry to humid conditions (ε′ from ∼4 to 8, σTHz 75 to 150 S/m, respectively). When compared to other photocatalysts, the THz dielectric response of CNx and especially humid K-PHI is within range of well-known oxides such as TiO2 that can efficiently generate charges from excitons, due to low exciton binding energies resulting from high ε′. The importance of dielectric property characterization on functionally relevant frequencies is thus highlighted, especially in the THz gap (0.1 – 10 THz), to understand the photophysical behaviour of organic semiconductors, even in the presence of water and hydrated ions. Such THz complex permittivity determination may also be beneficial for exploring next generation photo(electro)catalysts, electronics or ionotronics, and for computational property predictions that often require knowledge of ultrafast photophysical properties.
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Journal articleKafizas A, 2026, , NPG Asia Materials, Vol: 18, ISSN: 1884-4049
Cobalt phosphate (CoPi) is a widely used oxygen evolution reaction (OER) catalyst in photoelectrochemical (PEC) water splitting systems. Traditionally, CoPi is fabricated via photo-assisted electrodeposition (PED) from a cobalt-containing electrolyte solution, a method that is limited in scalability. In this study, we demonstrate a novel and scalable route to CoPi, where cobalt oxide (CoOx) is first grown by aerosol-assisted chemical vapour deposition (AACVD) and then surface modified through a dark electrochemical treatment (ET) process. Both fabrication techniques were used to deposit CoPi onto bismuth vanadate (BiVO4) photoanodes synthesised by AACVD. CoPi-decorated BiVO4 fabricated via AACVD + ET demonstrated superior charge separation efficiency, stability over four hours of chronoamperometry, and photoelectrochemical performance, achieving an improved half-cell solar-to-hydrogen (HC-STH) efficiency of 1.16% at 1.23 V vs RHE compared to CoPi-decorated BiVO4 fabricated by PED, which exhibited an HC-STH efficiency of 0.60%. These promising results highlight the potential of AACVD, conducted under atmospheric pressure, to enable the future development of both co-catalysts and scalable photoelectrode fabrication for large-area applications.
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Journal articleYe B, Burdis C, Mints V, et al., 2026, , ACS Energy Letters, Vol: 11, Pages: 1907-1915, ISSN: 2380-8195
Continuous electrochemical lithium-mediated ammonia production has shown promising performance. For this reaction, water oxidation could provide a direct route for proton supply, eliminating the need to generate molecular hydrogen. However, recent studies have reported low Faradaic efficiency for ammonia when water is used directly as the proton source. In this work, we integrate an electrically isolated Pd membrane to transfer protons generated from water oxidation into a nonaqueous lithium-mediated nitrogen reduction system. By employing Pd as a proton- and electron-conducting membrane rather than solely as a cathode, we enabled continuous operation in a flow-cell configuration, achieving a Faradaic efficiency of 36 ± 4% at a current density of −6 mA cm–2 over 6 h. Online mass spectrometry confirmed that the produced ammonia contained protons generated by water oxidation. This approach to using Pd provides a practical strategy for proton transport and establishes a viable device configuration to advance electrochemical lithium-mediated nitrogen reduction toward sustainable green ammonia synthesis.
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Journal articleHe T, Benetti D, Tseng C, et al., 2026, , Journal of the American Chemical Society, Vol: 148, Pages: 4833-4838, ISSN: 0002-7863
Despite its central role in photoelectrochemical (PEC) water splitting, the mechanistic pathway of water oxidation on metal oxides remains unresolved, with population-based and Butler–Volmer (BV) models offering distinct views on how surface valence band holes drive the reaction. Here, we bring together these two perspectives by combining operando photoinduced absorption (PIA) spectroscopy with photocurrent analyses on α-Fe2O3 (hematite) photoanodes as a function of light intensity. We find a crossover from population-controlled, rate law water oxidation at low hole densities to a BV-like, potential driven regime at high densities, triggered by band edge unpinning once surface M–OH species are fully oxidized, and excess holes accumulate without compensation. This mechanistic transition unifies competing models of interfacial charge transfer and reveals design principles for optimizing water oxidation in metal oxide photoelectrodes.
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Journal articleTian L, Sachs M, Verga LG, et al., 2026, , Chemical Science, Vol: 17, Pages: 4203-4212, ISSN: 2041-6520
Ultrafast small-polaron formation profoundly shapes the electronic and catalytic behaviour of transition metal oxides (TMOs). Despite its significance, spectroscopic investigations of photoexcited polaron hopping in TMOs have been scarcely explored. Here, we present the first optical spectroscopic observation of photoexcited small-polaron hopping across the first-row TMOs, using femtosecond transient absorption spectroscopy. This polaronic feature rises within 500 fs as Drude-type absorption converts to localized, polaronic absorption. Fitting with a small-polaron optical conductivity model yields polaron relaxation energies of 400–650 meV, evidencing substantial energy loss upon self-trapping. Kinetic analysis shows that oxides with open d-shells localize charge most readily: polaron formation activation barriers are low in all TMOs (0–10 meV), whereas hopping barriers remain much higher (200–350 meV). This work establishes key spectroscopic and kinetic insights, highlighting the trade-off between charge localization and mobility, as well as the critical role of polaron formation in TMOs photocatalysts.
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Journal articleAlimard P, Li L, Cazaly S, et al., 2026, , Carbon, Vol: 246, ISSN: 0008-6223
This study showcases how carbonaceous materials, including graphene (G), fullerene (F), and multi-walled carbon nanotubes (MWCNTs), can be integrated within titanium dioxide (TiO2) films as either: (i) mixed or (ii) layered sandwich structures (TiO2/carbonaceous material/TiO2) and show bifunctional photocatalytic activity. Our composites are engineered to address both NOx pollution and water splitting within the same platform. In the mixed composite (TGmix), graphene's high conductivity and electron-accepting ability enhance the photo-oxidation of NOx, where under UVA light 17.6 % NO and 9.6 % total NOx removal was seen, which was significantly higher than TiO2 alone, which showed 6.8 % NO and 1.3 % total NOx removal. Whereas in the sandwich-layered composite (TGT), the architecture promotes hole accumulation on the surface, favouring water splitting, with incident-photon-to-current efficiency (IPCE) reaching 68 % at 1.23 VRHE (pH = 7) under 250 nm illumination; a factor of ∼2 increase compared to TiO2 alone. Transient photocurrent (TPC) and diffuse reflectance transient absorption spectroscopy (DR-TAS) were employed operando to probe the kinetics of electron extraction and hole-mediated water oxidation. At 1.23 VRHE, the TGT sample showed slightly faster electron extract kinetics to T (TGT: t50 %–0.25 ms and T: t50 %–0.268 ms), along with a significantly higher long-lived hole carrier population that drove water oxidation, which were found to linearly correlate with the observed photocurrent density.Our wholistic study, including in operando investigations, informs the rational design of active carbonaceous composite coatings within anatase TiO2 that can be grown at scale for applications in NOx air pollution remediation and solar water splitting.
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Journal articleXie J, Tam B, Cai Y, et al., 2025, , Inorganic Chemistry Frontiers, Vol: 12, Pages: 8785-8799, ISSN: 2052-1545
This study demonstrates that the integration of plasmonic palladium (Pd) nanoparticles between a bismuth vanadate (BVO) coating and an electrode interface can significantly improve solar-driven glycerol oxidation. Pd nanoparticles of controllable shape, size and coverage were produced using a novel aerosol-assisted chemical vapour deposition (AACVD) synthetic route and then coated with BVO using the same technique. The nanoparticles enhanced visible light absorption and crystallinity. At 1.23 VRHE, the photocurrent density of bare BVO increased from 0.62 mA cm−2 in the absence of glycerol to 1.20 mA cm−2 with 0.5 M glycerol. When Pd nanoparticles were incorporated beneath BVO, the photocurrent further increased from 0.86 mA cm−2 without glycerol to 1.58 mA cm−2 with 0.5 M glycerol, and the incident photon-to-current conversion efficiency (IPCE) boosted from ∼15% to ∼40% at 400 nm. Ultra-fast transient absorption spectroscopy suggests that the addition of Pd nanoparticles introduces additional charge transfer pathways, including hot electron injection and plasmon-coupled states, which prolong carrier lifetimes and suppress recombination. These combined effects provide a promising strategy to improve the efficiency and durability of photoelectrochemical devices for sustainable fuel generation and selective organic oxidation reactions.
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Journal articleLi H, Lin Z, Guo F, et al., 2025, , ACS Applied Energy Materials, Vol: 8, Pages: 17334-17345, ISSN: 2574-0962
This study employs aerosol-assisted chemical vapor deposition (AACVD) to fabricate WO3/BiVO4 heterojunction photoanodes with an inverted architecture (WO3 atop BiVO4). The unique permeable nanofiber morphology of WO3 provides a solution to enhance water oxidation performance. By correlating precursor volume (10–40 mL) and spatial position within the deposition chamber (inlet/mid/outlet) with film properties, we demonstrate that a midreactor position yields “grass-like” WO3 nanofibers (diameter: 100–230 nm, length: 3.5–3.98 μm), enabling dual functionality: (i) > 50% light transmittance to the underlying BiVO4 absorber, and (ii) electrolyte penetration into the heterointerface between WO3 and BiVO4. In contrast, rod-like WO3 produced near the inlet causes severe light scattering, reducing the incident photon-to-current efficiency (IPCE) by six times above wavelengths of 350 nm. Optimized samples, produced with a deposition volume of 30 mL to deposit WO3 atop of BiVO4 positioned in the middle of the deposition chamber (i.e., WO3-30/BiVO4-mid), achieve a photocurrent density of 0.82 mA·cm–2 at 1.23 VRHE under 1 sun irradiance, which is 121% higher than single-layer BiVO4 (0.37 mA·cm–2) and exceeds some conventional WO3-under/BiVO4 heterojunctions in which WO3 is underneath BiVO4. Transient absorption spectroscopy confirms prolonged carrier lifetimes in our unique heterostructure through improved charge-carrier separation. This work challenges current traditional heterojunction design rules for the WO3/BiVO4 system by showcasing how permeable WO3 nanostructures atop BiVO4 photoanodes can improve light harvesting and facilitate charge-carrier separation to significantly improve activity.
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Journal articleWaehayee A, Ngamwongwan L, Kafizas A, et al., 2025, , Chemical Engineering Journal, Vol: 519, ISSN: 1385-8947
The wide range of potential applications for photocatalysis has made research on photocatalytic materials highly active. However, various limitations hinder large-scale applications of photocatalysis, making the search for novel and improved catalysts an ongoing pursuit. To achieve this, a detailed analysis of material characteristics and charge transfer behavior is crucial. This study investigates the enhancement of Bi2MoO6 (BMO) photocatalytic performance through iodate (I5+) substitution, focusing on its impact on charge transport and reaction efficiency. Employing experimental and computational methods, we propose that carrier migration in Bi2MoO6 follow a small polaron model. Substituting I5+ into Bi2MoO6 increase the exposure on {100} facets, where polaron hopping along the facet is easier than on the exposed {010} facet of pristine Bi2MoO6. Moreover, this substitution creates defects and increases charge carrier concentration by approximately threefold. The increased Fermi energy level enables I-doped Bi2MoO6 to generate H2 and enhance p-nitroaniline reduction activity. As a result, the catalyst exhibits nearly 10 times higher efficiency in both reactions. This work highlights a defect-engineering strategy that potentially involves polaronic transport to improve photocatalyst design, offering a promising solution for sustainable energy applications, including water splitting and selective organic transformations.
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Journal articleHwang GB, Heo KJ, Jee W, et al., 2025, , ACS Nano, Vol: 19, Pages: 27740-27753, ISSN: 1936-0851
Here, we present the effect of 1.2–9.9 nm Au particles on crystal violet-treated polymer under a low intensity of visible light. The use of Au particles ≤ 6.3 nm promoted charge carrier transfer from crystal violet to Au particles. Photospectroscopy analyses and DFT computations revealed that a change in the electronic band structure caused by the size reduction of the particle altered the charge carrier transfer pathway in crystal violet. Especially for crystal violet─1.2 nm Au particles, charge carrier transfer predominantly occurs at the S1 of crystal violet because the T1 state lacks sufficient potential energy for transfer. 1.2 nm Au particles on crystal violet not only most significantly enhanced the generation of O2•–, H2O2, and •OH by minimizing unnecessary side reactions or energy loss but also showed the most potent disinfection activity against Staphylococcus aureus, even at low visible light flux levels (0.037–0.054 mW cm–2), which resulted in a 5.3 log reduction in viable bacteria after 6 h exposure to visible light. This finding provides fundamental insights into the Au effect as a cocatalyst in photocatalysts and the development of light-activated self-sterilizing surfaces that can be applied to various hospital surfaces to prevent the spread of pathogens, which remains a global challenge.
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Dr. Andreas Kafizas
Leader - Solar Coatings Group
e-mail: a.kafizas@imperial.ac.uk
tel: +44(0)20 7594 6752
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