The present work describes the synthesis of mesoporous Mn2O3-TiO2 (TiMn) and Ag-integrated TiMn (TiMnAg) nanocomposites, and their superior photocatalytic activity in a thin-film form was demonstrated for solar H-2 generation in direct sunlight. The integration of metallic Ag and TiMn significantly enhanced solar H-2 production due to the combined effect of Schottky junction and heterojunction formation. The PIRET (plasmon-induced resonance energy transfer) effect of Ag and the consequent energy transfer to the surrounding lattice, and heterogeneous distribution of metal ions on the TiO2 surface with possible synergistic interactions among them, are additional reasons for efficient solar-to-chemical energy conversion. TiMnAg-1 (0.5 wt % Ag-loaded on TiMn) and TiMn-3 (TiO2:Mn = 1:0.03 mol ratio) showed the highest H-2 production rate (9.05 mmolh(-1)g(-1)), which is 60 times higher than that of bare TiO2 (0.16 mmolh(-1)g(-1)). TiMnAg-1 fabricated in a thin-film form shows 5.2 times higher solar H-2 production activity than its powder counterpart. The interconnected mesoporous network in TiMnAg-1 is an additional advantage, which enhances diffusion and mass transfer during the reaction. The plausible photocatalytic reaction mechanism of the TiMnAg nanocomposites involves direct energy and electron transfer from metallic Ag nanoparticles and Mn2O3 species, respectively, to TiO2, which is then utilized for the reduction of H+ to H-2.

Sustainable and efficient photocatalytic conversion of small molecules to liquid fuels/chemicals needs a large extent of charge separation at heterojunctions and equal charge utilization at redox sites. Toward achieving this, visible-light absorbing CeO2 quantum dots (CeQDs) are directly assembled from the precursors (Ce3+ and OH-) into the TiO2 nanopores by the successive ionic layer adsorption and reaction method, and are subsequently integrated structurally and electronically. Assembly of CeQDs into TiO2 leads to a sub-trillion number of heterojunctions in 1 mg photocatalyst material. Concurrent activation of water and methane generates active radicals that help in selective ethanol and a minor amount of acetone formation. Product generation is further enhanced by deliberate reduction of the photocatalyst device, which enhances Ce3+ content and broadens the valence band with a significant change in electronic structure. The detailed analysis of the photocatalyst device and photocatalysis results reveals the charge transfer mechanism and the reaction pathway.

Current study elucidates the electrocatalytic efficacy of palladium-nanocubes (Pd-NCs) for the selective oxidation of glucose to value-added chemicals with concomitant hydrogen evolution. The Pd-NC catalyst demonstrated exceptional activity and product selectivity, achieving nearly quantitative glucose conversion (>99 %) with high gluconic and glucaric acid yield at low anodic overpotential (0.6 V vs. RHE) in alkaline electrolyte. At not-so-high elevated potentials (1.2 V vs. RHE), oxidative CC scission prevails, yielding shorter-chain carboxylates along with C6-acids. Reaction products are thoroughly characterized and quantitatively estimated by NMR spectral methods; NMR methods also provide CC cleavage and mechanistic pathways of glucose to various products. Complementary DFT calculations delineate the thermodynamic favorability of glucose adsorption on Pd-NC surfaces (-1.83 eV) and the exergonic oxidation pathway under applied bias, corroborating experimental product distributions. In a two-electrode electrolyzer, Pd-NC anode paired with Pt/C and Ni2P cathode demonstrates 100 mA/cm(2) at 0.99 V and 1.37 V, respectively, with 48 % reduction in energy input (26.6 kWh/kg H-2) compared to conventional alkaline electrolysis; critically, H-2 production energy is lower than the usable energy (33.3 kWh/kg H-2). Sustainable chronopotentiometric assays confirm sustainability (similar to 140 h) in alkaline as well as saline electrolytes, underscoring the system's resilience against chloride-mediated corrosion. Present work establishes a proof of concept for integrated biomass-component valorization and carbon-negative green hydrogen production, merging atomic-level mechanistic insights with scalable reactor design. Optimization of reaction parameters, including potential tuning, reaction temperature and electrolyte engineering, offers a compelling strategy to further enhance C6 and fragmented product selectivity and overall system efficiency.

Integrating glycerol oxidation with water electrolysis offers a sustainable route for hydrogen production while enabling concurrent generation of industrially relevant C1-C3 value-added materials. This system replaces kinetically sluggish oxygen evolution reaction (OER) simultaneously delivering H-2 at the cathode with high turnover frequency, thereby lowering the overall cell voltage and enabling the valorization of glycerol, a major by-product of the biodiesel industry. However, the development of an efficient bifunctional electrocatalysts capable of driving cathodic as well as anodic half-cell reactions remains a key challenge. Herein, we present a cerium-cobalt oxide composite modified with an amorphous carbon layer (Ce,Co-O/C) as an effective bifunctional catalyst for glycerol-assisted water electrolysis. The interfacial electron distribution across the Co-Ce oxide heterojunction generated abundant redox-active sites and accelerates reaction kinetics, while the conductive carbon layer facilitates rapid charge transfer and imparts improved stability. Consequently, the Ce, Co-O/C catalyst exhibited high formate selectivity at 1.4 V (vs RHE) at room temperature and delivers a low cell voltage of 1.90 V at 100 mA cm(-2) in a symmetric Ce,Co-O/C vertical bar vertical bar Ce,Co-O/C system, maintaining operational stability over 100 h. This work provides a promising interface-engineering for designing self-supported bifunctional electrocatalysts toward integrated biomass assisted co-electrolysis systems.

Doping of SrFeO3-delta with transition and non-transition elements provides a powerful route to modulate its physicochemical properties. In this investigation, a series of ruthenium and silicon co-doped SrFeO3-delta (SrFe0.95-xRu0.05SixO3-delta) samples were prepared via the sol-gel combustion method using hexamine as fuel. The doped samples crystallized in the cubic structure with the Pm3m (221) space group. The presence of Si4+, Fe3+, Fe4+ and Ru4+ in the SrFe0.95-xRu0.05SixO3-delta sample was confirmed by XPS analysis. The presence of an EPR signal at g = 1.9393 and the temperature-programmed desorption of oxygen (TPD-O2) analyses validated the presence of oxygen vacancies. The ruthenium and silicon co-doped SrFeO3-delta effectively hydrogenates biomass-derived platform molecule furfural with 95% conversion and exhibits 88% furfuryl alcohol selectivity at 185 degrees C for 6 h under 30 bar H2 pressure. The spent ruthenium-doped SrFeO3-delta (SrFe0.95Ru0.05O3-delta) catalyst exhibited a phase transformation from the cubic perovskite structure to the brownmillerite phase with the exsolution of the metallic ruthenium species. The exsolution of metallic ruthenium can be correlated with the formation of secondary products, viz., non-selective hydrogenation leads to tetrahydrofurfuryl alcohol, furan, and methylfuran. Ruthenium and silicon co-doped perovskite oxide showed selectivity towards furfuryl alcohol with the retention of its original cubic perovskite structure. This modification of perovskite oxide with ruthenium and silicon demonstrates a highly effective strategy for engineering stable and chemo-selective catalysts for the sustainable upgrading of platform chemicals.

Present work describes a sol‐gel assisted one‐pot synthesis of mesoporous Fe₂O₃‐TiO₂ nanocomposites (TiFe) with different Ti:Fe ratios, and fabrication of Ag‐integrated with TiFe nanocomposites (TiFeAg) by a chemical reduction method and demonstrated for high solar H2 generation activity in direct sunlight. Enhanced solar H2 production is attributed to the light absorption from entire UV+Visible region of solar spectrum combined with Schottky (Ag‐semiconductor) and heterojunctions (TiO2‐Fe2O3), as evidenced from HRTEM and various characterization studies. TiFeAg‐2 thin film (1 wt% Ag‐loaded TiFe‐4) displayed the highest activity with a solar H2 yield of 7.64 mmol h⁻¹g⁻¹, which is 48 times higher than that of bare TiO₂ and 5 times higher in thin film form compared to its powder counterpart. Schottky and heterojunctions formed at the interface efficiently separate the charge carriers and increase the hydrogen production activity. The highest H2 production activity of TiFeAg‐2 is partly attributed to the heterogeneous distribution of Fe3+ and metallic Ag‐species with relatively high Ag/Ti surface atomic ratio. A plausible photocatalytic reaction mechanism on TiFeAg nanocomposite may involve the direct electron transfer from both Fe2O3 and TiO2 to Ag nanoparticles which are subsequently utilized for the reduction of H+ to H2.

The integration of the electrochemical glycerol oxidation reaction (GOR) with the hydrogen evolution reaction (HER) has emerged as a promising alternative to the sluggish oxygen evolution reaction (OER) in water splitting toward the development of renewable and clean energy sources. However, suitable electrodes that facilitate redox kinetics while increasing the selectivity of the desired product(s) are still required. Herein, a series of europium oxide (Eu2O3) anchored on graphitic carbon nitride (g-CN) nanoaggregates (g-CNEux, x = 1, 5, and 10) with different Eu contents were synthesized for electrolysis of water and glycerol. g-CNEu1 showed the lowest overpotentials for the respective redox reactions of water splitting and GOR indicating its multifunctional activities with longtime stability. Moreover, GOR coupled HER showed faster kinetics over water splitting due to facile counter anode reactions with 16 mV lower overpotential to reach 100 mA cm(-2) current density. The prepared electrocatalysts exhibited superior activity toward C-C bond cleavage, achieving formate production selectively in the GOR (79.8 % over 12 h at 1.4 V) among the C1-C3 products.

Photocatalytic water splitting is considered one of the efficient methods for producing green hydrogen. However, the sluggish oxygen evolution reaction (OER) kinetics with four electrons limits the overall efficiency of water splitting. Biomass components/biomass derivatives are renewable carbon feedstocks that are abundantly available in nature. It is prudent to make use of electrons and holes concurrently in photocatalysis for H2 production and oxidation of biomass components, respectively, due to the latter's occurrence at a lower potential (≤1 V) than that of the OER (>1.23 V), to value-added products (VAPs); this approach makes the entire process energy-efficient and kinetically superior. This potential approach could effectively utilize the charge carriers and abundant renewable resources of water and biomass simultaneously, meeting the sustainability, energy conversion and economic goals together. Parallel utilization of the charge carriers for redox reactions also enhances the sustainability of the catalyst system employed. Interestingly, biomass component oxidation to VAPs occurs in several steps, which not only enhances hole utilization but also provides an opportunity to design better catalysts to enhance the selectivity of the target products. Carrying out such reactions under aerobic or anaerobic conditions and different pH conditions allows fine-tuning of the product selectivity. The current review provides a detailed overview of the recent developments in this emerging area with three different types of photocatalyst systems, namely, oxide-, chalcogenide-, and carbon-based materials. Among these, the oxide-based systems generally demonstrate the highest activity with sustainability, maintaining performance for several hours. While many of these systems exhibited high selectivity towards a single product, 100% selectivity to lactic acid from glycerol was observed with a BiVO4-integrated TiO2 catalyst. Finally, the challenges, opportunities and future perspectives in this thriving field are listed, and they underscore the role of a carbon-neutral economy towards achieving a potentially sustainable future.

Multiphasic titania has been prepared to study the role of multiple heterojunctions on the charge transfer dynamics and resultant photocatalytic hydrogen production. Through an acid regulated hydrothermal method, four materials with following phase compositions were prepared viz. single phase anatase and rutile, biphasic anatase-rutile and triphasic anatase-brookite-rutile. The phase compositions of the materials were confirmed through XRD and HRTEM studies. The biphasic and triphasic materials were found to be highly nanoparticulate in nature while forming numerous and diverse heterojunctions. In the triphasic material, various binary and ternary heterojunctions were observed. These heterojunctions performed in harmony to ensure efficient charge transport as shown by the low charge transfer resistance and high electron lifetime. This subsequently ensured a high reduction capability and photocurrent response. This all culminated into the triphasic material outperforming all other materials in solar photocatalytic hydrogen production. The H2 yield from the triphasic material was 81% and 40% higher than the pristine anatase and the biphasic material respectively. Additionally, by using the triphasic material in thin film form, a 4-fold increase in the hydrogen yield with a high apparent quantum efficiency of 8.2 % was achieved over the particulate form. The superior charge transport and photocurrent response due to the greater varied heterojunction formation in the anatase-rutile-brookite material as opposed to that in the biphasic material led to this superior performance. Thus, multiple heterojunctions, in this case, a triphasic heterojunction of anatase, rutile and brookite phases opens up a new avenue of research for efficient green hydrogen production.

Achieving economical and sustainable artificial photosynthesis (APS) in direct sunlight for liquid fuel production with high efficiency remains an important challenge. A major obstacle in the photoelectrochemical (PEC) oxidation of organic compounds is attaining high selectivity with the desired product(s). This study introduces a novel strategy by integrating BiVO 4 quantum dots (BVQDs), structurally and electronically, into the nanopores of commercial TiO 2 (BVT for BVQDs integrated in pores of TiO 2 ) to improve solar‐driven photocatalysis. The band gap of the BVT photoanode decreases to 2.53 eV as compared to pure TiO 2 (3.2 eV), which enhances visible light absorption and charge separation. BVT with Pt as a co‐catalyst acts as an APS system, which selectively oxidizes glycerol into lactic acid (100% selectivity at 1 mM glycerol) and glyceric acid (98% selectivity at 100 mM), while simultaneously generating green hydrogen. Selectivity of the product can be further controlled by anaerobic or aerobic conditions as well as the length of the reaction time. Direct integration of BVQDs into TiO 2 mesopores significantly enhances charge separation as well as utilization at redox sites. Current work provides key insights into optimizing photocatalytic conditions for highly selective value‐added chemical production, which highlights the sustainability and efficacy of TiO 2 ‐based semiconductors with quantum dot integration.

The ever-increasing demand for sustainable solutions for eliminating environmental pollutants, solar energy harvesting, water splitting, etc. have led to the design and development of novel materials to achieve the desired result. In this regard, structurally and electronically integrated (SEI) BiVO4-TiO2 (SEI-BVT) with abundant heterojunctions has emerged as a promising entity for efficient charge separation, which in turn enhances artificial photosynthesis (APS) activity. The present work adopted a unique synthetic strategy using SILAR to fabricate SEI-BVT from ionic precursors (Bi3+ and VO43-) into the pores of TiO2, exhibiting benchmark APS efficiency compared to the individual components. This preparation results in approximately 180 trillion uniformly distributed heterojunctions in 1 mg cm-2 of the SEI-BVT photoanode material. Charge carriers in SEI-BVT and BiVO4 are similar; however, the recombination is highly hindered when SEI-BVT heterojunctions are formed in the former. Our earlier work demonstrated 31-38% solar-to-fuel efficiency (STFE) with BiVO4-TiO2 for APS in the presence of the Pd-nanocube co-catalyst. The emphasis of the current work is to explore the dynamics of the light-induced processes in these heterojunctions to understand the interfacial charge transfer process. Femtosecond transient absorption (TA) spectroscopy has been employed to monitor the excited state dynamics. Our results show that new trap states have evolved under light illumination, which are significantly long-lived and hinder charge recombination, and consequently enhance STFE. A significantly large number of charge carriers exhibit a lifetime of ≫6 ns with visible light photons, at least up to 720 nm, which is higher than the band-gap absorption onset at 490 nm for SEI-BVT compared to bulk BiVO4. The rate of formation of charge carriers is significantly affected in the heterojunctions.

In the pursuit of sustainable green hydrogen production, the electrooxidation of abundantly available carbon-containing molecules at a significantly low voltage presents a promising pathway, helping to reduce the cost of hydrogen generation while simultaneously yielding value-added chemicals/fuels. In the current study, we report the template-free green synthesis of ZnCo2O4 directly on Ni-foam (NF), demonstrating anodic stability and bifunctional electrocatalytic activity toward alkaline (1 M KOH) glycerol oxidation over an extended duration of 230 h at 50 mA cm- 2. The catalyst's high electrochemical surface area contributes to its remarkable performance, enabling sustained high current density. Compared with monometallic (ZnO or Co3O4) oxides, ZnCo2O4 oxide reveals superior catalytic performance. The two-electrode electrolyzer setup (ZnCo2O4 oxide/NF || ZnCo2O4 oxide/NF) operates at a significantly low cell potential of 1.9 V to achieve 100 mA cm- 2 in 0.2 M glycerol, which is 180 mV lower than that of conventional 1 M KOH solution. The three-electrode setup achieved 1 A/cm2 current density at 1.907 V vs RHE. Both anodic and cathodic processes exhibit high Faradaic efficiency, achieving 98% efficiency for H2 and 90% selectivity toward formate generation, along with significant methanol production. This demonstrates efficient C-C bond cleavage capability with glycerol to predominantly C1-products. The electrocatalytic formate production from alkaline glycerol using ZnCo2O4 offers an energy-efficient pathway, facilitating carbon-negative green hydrogen generation, thus contributing to a cleaner and sustainable energy landscape.

The transition metal selenides (MxSey) have gained attention for their unique physical and chemical properties, especially those associated with the transition metal (M). Despite advancements in synthesis, fabricating these selenides is challenging due to their complex stoichiometry and high asymmetry. One such system is monoclinic iron selenide (Fe3Se4), which can be used in permanent-magnet technologies and serve as a model system for understanding magnetism. This study focuses on fabricating monoclinic M3Se4 (M = Fe, Co, or Ni) compounds via thermal decomposition, examining how solution chemistry influences their morphology and properties. With a Curie temperature of about 322 K, Fe3Se4 is ferrimagnetic, whereas Co3Se4 and Ni3Se4 are paramagnetic between 5 and 300 K. The latter two compounds also show higher catalytic activity for hydrogen evolution in water splitting, with maximum H2-evolution rates of 1.01, 5.16, and 6.83 mmol h-1g-1 for Fe3Se4, Co3Se4, and Ni3Se4, respectively.

Nickel-doped lanthanum aluminium perovskite, LaAl1-xNixO3-delta with x = 0, 0.1, 0.2, 0.3, 0.4,0.5, 0.6, and 0.75 (LANx), were obtained through a combustion method followed by a calcination process. The obtained LANx materials crystallized in the cubic structure by the Pm-3m (221) space group. The nanocrystalline nature of the LANx materials was confirmed by the average crystalline size determined using Debye-Scherrer formula. X-ray photoelectron spectroscopy (XPS) studies showed that nickel was present in the +2 and +3 oxidation states. The introduction of nickel resulted in distinct peaks in TPR in the temperature range of 200-600 degrees C, with an enhanced reducibility of the materials. The LANx materials were thoroughly assessed for their effectiveness in the hydrogenation of cinnamaldehyde. The maximum catalytic activity (cinnamaldehyde conversion of 98% with a hydrocinnamylalcohol selectivity 96.5%) was observed with the presence of the LAN7 catalyst at 150 degrees C for 6 h at a H2 pressure of 10 bar. The catalytic activity is maintained even after four cycles, which broadens the application scope as the material is sustainable, scalable, cost-effective, and a potential alternative to reported noble metal catalysts. The synergistic effect of nickel and oxygen vacancies in the catalyst improves the reducibility and provides a promising catalytic activity in the cinnamaldehyde hydrogenation.

A series of thin-film photocatalysts comprising TiO2 modified with carbon dots (CDs) dispersed either with palladium (Pd-CD/TiO2) or nickel (Ni-CD/TiO2) were synthesized via solid-state and wet-impregnation methods. Morphological characterization (HR-TEM, SEM-EDS) confirmed the anatase phase of TiO2 and the atomic dispersion of metal-integrated CDs on its surface. UV-vis DRS and XPS analyses revealed a marginal red shift in band-gap and the presence of sp2-hybridized graphitic carbon, and metal-carbon interactions, indicating enhanced light absorption and charge separation through Schottky junctions. Under direct sunlight illumination, Pd-CD/TiO2 thin film exhibited superior hydrogen yield (1167 µmol g-1 h-1) and maintained stability over 25 h, outperforming Ni-CD/TiO2 (494 µmol g-1 h-1) and bare TiO2 (166 µmol g-1 h-1) photocatalyst thin films. Concurrent glycerol oxidation at neutral pH (pH∼7) yields glycolaldehyde (41% selectivity), formic acid, and dihydroxyacetone as value-added products. Enhanced photocurrent density and lower impedance of Pd-CD/TiO2 corroborate improved charge carrier separation and dynamics. The results demonstrate that Pd-CD synergistically improves the photocatalytic performance of the Pd-CD/TiO2 for sustainable hydrogen generation and selective biomass valorization.

Methane activation (MA) to platform chemicals under ambient conditions still remains an open challenge to be fully realised. The present work shows the fabrication of CeVO4 quantum dots (CV-QDs) by a bottom-up approach; they are assembled from Ce3+ and metavanadate ions, and structurally and electronically integrated into the micro-/meso-pores of TiO2 (CV-QD-TiO2 (CVT)), demonstrating the conversion of MA to ethanol/ethylene by visible light-driven photocatalysis. CV-QDs in confined pores modify the quantum confinement effects and are characterized by physicochemical methods. The current synthetic strategy is potentially scalable and results in sub-quadrillion heterojunctions in a 1 mg CVT photoanode spread over 1 cm2. MA with CVT under one-sun conditions demonstrates similar to 100% selectivity to ethanol, yielding 4.36 mu mol h-1 cm-2, with a solar-to-fuel efficiency (STFE) of 0.56. Further, by employing a co-catalyst, significant STFE (5.08) and yield (39.5 mu mol h-1 cm-2) are achieved selectively towards ethylene. A deliberate addition of methanol increases the rate of ethanol production by 17.2 times, indicating that the methyl-methoxy interaction is the origin of C-C coupling. Weight is normalized to a gram of CV-QDs in a large area CVT photoanode to yield 109 mmol h-1 gCV-QD-1 of ethanol and 988 mmol h-1 gCV-QD-1 of ethylene. Enhanced activity and selectivity towards the C2-product is attributed to band-edge modulation and trillions of heterojunctions, which in turn facilitate charge separation and charge transfer for effective charge utilisation at redox sites.

Zinc oxide (ZnO) hexagonal nanorods and silver (Ag)- ZnO nanoplate like structures are synthesized by using novel natural carbon templates. The structural intricacies are evaluated with various characterizations which is utilized for supercapacitor and photocatalytic H2 production under direct sunlight applications. The role of carbon template in silver ion dispersion on ZnO matrix which is reflected in XRD and optical measurements. The presence of Ag (111) plane in the ZnO matrix, as proved by XRD shifts the Fermi level which in turn facilitates electron transport from valence band to conduction band whilst it is useful for photocatalytic H2 production. The UV-DRS shift in wavelength to visible region is observed with the introduction of silver on ZnO. The HRSEM and HRTEM reveals the presence of nanorods and plate like morphology with distinct Ag (111) lattice fringes. XPS gives insight about the oxidation state of Ag-ZnO nanocomposites which is also complimented from peaks in XRD and LSPR in UV-DRS. Silver presence in both oxidation state attributed to Ag2O (Ag+) and metallic silver cluster (Ag0). The BET isotherm substantiates increased surface area for the Ag5 %-ZnO (PC) composite than Ag5 %-ZnO (Egg white-EW), since the former provides fine dispersion of Ag on ZnO matrix. The electrochemical investigations reveal that the material with higher surface area provide more active sites for superior specific capacitance (221.1 F g-1) and high energy density (27.6 Wh kg-1) with 88 % capacitance retention stability which is clearly evidenced from GCD analysis. The lower charge transfer resistance of Ag-ZnO nanocomposite is beneficial for energy conversion and storage applications. The usage of silver in ZnO enhanced the antifungal activity against aspergillus niger fungi.

Solar hydrogen production by photocatalysis has long been considered as an important energy option. Whichever photocatalyst succeeds, methods should be available to scale-up in a most sustainable and cost-effective manner, and the present work addresses this specific issue. In the present study, Ce-doped in the TiO2 lattice (Ce-TiO2) and the same integrated with CNT (CNT-Ce-TiO2; (CCT)) composite was synthesized and characterized. Current study demonstrates the synergistic integration of Ce-TiO2 as a light absorber and charge generator with CNTs as efficient charge separation at heterojunctions as well as charge transporter in a thin-film configuration (lab-scale (4.7 cm(2)), bench-scale (500 cm(2))). Improved H-2 generation under direct sunlight demonstrated in thin film form, than in particulate suspension, is attributed to efficient light absorption, particularly for electron-hole pair separation and their dispersion to redox sites. Additionally, the role of the binder is highlighted for improving H-2 yield and the sustainability of the thin-film form of photocatalyst. similar to 200 mg (1 g) CCT coated over 500 cm(2) (2500 cm(2)) photocatalyst produced 21.6 mmol/h (102 mmol/h) H-2 in sunlight. Present results provides a proof of concept that the thin film form of photocatalyst displays, at least 10 times, higher H-2 yield than its powder counterpart, depending on the measurement conditions. A non-linear enhancement in H-2 yield with small and large area thin-film indicates complex underlying factors and highlights the scope for further improvements.