Facile synthesis of hierarchical core-shell carbon@ZnIn2S4 composite for boosted photothermal-assisted photocatalytic H2 production.

Against the backdrop of energy shortage, hydrogen energy has attracted much attention as a green and clean energy source. In order to explore efficient hydrogen production pathways, we designed a composite photocatalyst with carbon-based core-shell photothermal-assisted photocatalytic system (Carbon@ZnIn2S4, denoted as C@ZIS). The well-designed catalyst C@ZIS composites demonstrated a photocatalytic hydrogen precipitation rate of 2.97 mmol g-1 h-1 even in the absence of the noble metal Pt co-catalyst. The incorporation of carbon-based core-shell photocatalysts into a photocatalytic reaction significantly affects the activity of the reaction by triggering a photothermal effect in the reaction solution. The results of the physicochemical experiments demonstrated that the carbon spheres in C@ZIS composite system could provide a greater number of active sites, thereby accelerating the electron transfer and separation efficiency, and thus enhancing the photocatalytic activity. The study presents an efficacious design concept for the development of efficacious carbon-based core-shell photothermal-assisted photocatalysts, which is anticipated to facilitate the efficient conversion of solar energy to hydrogen energy.

Optimizing photocatalytic hydrogen evolution performance by rationally constructing S-scheme heterojunction to modulate the D-band center.

The research in the field of photocatalysis has progressed, with the development of heterojunctions being recognized as an effective method to improve carrier separation efficiency in light-induced processes. In this particular study, CuCo2S4 particles were attached to a new cubic CdS surface to create an S-scheme heterojunction, thus successfully addressing this issue. Specifically, owing to the higher conduction band and Fermi level of CuCo2S4 compared to CdS, they serve as the foundation and driving force for the formation of an S-scheme heterojunction. Through in-situ X-ray photoelectron spectroscopy and electron paramagnetic resonance analysis, the direction of charge transfer in the composite photocatalyst under light exposure was determined, confirming the charge transfer mechanism of the S-scheme heterojunction. By effectively constructing the S-scheme heterojunction, the d-band center of the composite photocatalyst was adjusted, reducing the energy needed for electron filling in the anti-bonding energy band, promoting the transfer of photogenerated carriers, and ultimately enhancing the photocatalytic hydrogen production. performance. After optimization, the hydrogen evolution activity of the composite photocatalyst CdS-C/CuCo2S4-3 reached 5818.9 µmol g-1h-1, which is 2.6 times higher than that of cubic CdS (2272.3 µmol g-1h-1) and 327.4 times higher than that of CuCo2S4 (17.8 µmol g-1h-1), showcasing exceptional photocatalytic activity. Electron paramagnetic resonance and in situ X-ray photoelectron spectroscopy have established a theoretical basis for designing and constructing S-scheme heterojunctions, offering a viable method for adjusting the D-band center to enhance the performance of photocatalytic hydrogen evolution.

Construction of 2D/2D S-scheme Bi2MoO6/Zn-TCPP heterojunction via in-situ self-assembly growth strategy to enhance interface effect for efficient photocatalytic hydrogen production.

Two-dimensional/two-dimensional (2D/2D) heterojunctions are considered to be an effective strategy for forming strong interface effects and facilitating photogenerated carrier separation. However, it is usually limited by the size mismatch of the materials, even at the expense of its redox capability. Herein, 2D/2D S-scheme heterojunction photocatalyst Bi2MoO6/Zn-TCPP (BMO/ZTP) composed of 2D Bi2MoO6 and 2D Zn-TCPP (TCPP: tetrakis (4-carboxyphenyl) porphyrin) (MOFs) was constructed by in-situ self-assembly growth strategy. The size-compatible 2D/2D composites had abundant surface active sites and strong interactions. In addition, band bending and interfacial electric field (IEF) effect based on S-scheme heterojunction could accelerate the separation and migration of photogenerated carriers in BMO/ZTP. The best hydrogen precipitation rate of the BMO/ZTP was 10900.94 umol·g-1·h-1, which was 38.90 and 3.24 times higher than that of Bi2MoO6 (280.26 umol·g-1·h-1) and Zn-TCPP (3360.34 umol·g-1·h-1), respectively. The results indicated that 2D/2D BMO/ZTP S-scheme heterojunction could enhance the interface effect and retain strong reducing electrons to achieve efficient photocatalytic hydrogen production, which was confirmed by ultraviolet photoelectron spectroscopy (UPS), Tafel curve, electron spin resonance (ESR) and time-resolved photoluminescence (TRPL) characterization and density functional theory (DFT) calculations. This work provided a general strategy for constructing 2D Bi2MoO6 and 2D MOFs S-scheme heterojunctions to enhance interface effects for achieving efficient photocatalytic hydrogen production.

Hollow dodecahedral Zn0.3Cd0.7S@NiCo-mixed metal oxide p-n heterojunction with high-efficiency photocatalytic hydrogen production activity.

The growing demand for clean and sustainable energy has driven extensive research into efficient photocatalysts for hydrogen production. However, many semiconductor photocatalysts in this field still face the challenges such as wide band gap, limited visible light absorption, and inefficient separation and transport of photoinduced charges. In this study, nickel-cobalt layered double hydroxide (NiCo-LDH) was synthesized using an "etch-and-grow" method with zeolitic imidazolate framework-67 (ZIF-67) as a sacrificial template, followed by high-temperature calcination to produce nickel-cobalt mixed metal oxide (NiCo-MMO). Zn0.3Cd0.7S quantum dots were used to modify NiCo-MMO resulting in a hollow dodecahedral Zn0.3Cd0.7S@NiCo-MMO composite photocatalyst. In hydrogen production performance test, the optimized Zn0.3Cd0.7S@NiCo-MMO exhibited excellent performance (8177.5 µmol·g-1·h-1) and demonstrated good cycling stability. The hollow dodecahedral structure of the Zn0.3Cd0.7S@NiCo-MMO enhanced the light trapping ability and provided large surface area. The p-n heterojunction formed within Zn0.3Cd0.7S@NiCo-MMO accelerated carrier separation and transfer, effectively inhibited the recombination of photogenerated electrons and holes, and significantly improved the hydrogen production activity.

Iron-promoted zirconia-alumina supported Ni catalyst for highly efficient and cost-effective hydrogen production via dry reforming of methane.

Developing cost-effective and high-performance catalyst systems for dry reforming of methane (DRM) is crucial for producing hydrogen (H2) sustainably. Herein, we investigate using iron (Fe) as a promoter and major alumina support in Ni-based catalysts to improve their DRM performance. The addition of iron as a promotor was found to add reducible iron species along with reducible NiO species, enhance the basicity and induce the deposition of oxidizable carbon. By incorporating 1 wt.% Fe into a 5Ni/10ZrAl catalyst, a higher CO2 interaction and formation of reducible "NiO-species having strong interaction with support" was observed, which led to an ∼80% H2 yield in 420 min of Time on Stream (TOS). Further increasing the Fe content to 2wt% led to the formation of additional reducible iron oxide species and a noticeable rise in H2 yield up to 84%. Despite the severe weight loss on Fe-promoted catalysts, high H2 yield was maintained due to the proper balance between the rate of CH4 decomposition and the rate of carbon deposit diffusion. Finally, incorporating 3 wt.% Fe into the 5Ni/10ZrAl catalyst resulted in the highest CO2 interaction, wide presence of reducible NiO-species, minimum graphitic deposit and an 87% H2 yield. Our findings suggest that iron-promoted zirconia-alumina-supported Ni catalysts can be a cheap and excellent catalytic system for H2 production via DRM.

CoNi-layered double hydroxide derived CoS2/NiS2 dodecahedron decorated with ReS2 Z-scheme heterojunction for efficient hydrogen evolution.

The high efficient utilization of light absorption and the effective separation of photogenerated carriers are critical factors in enhancing the performance of photocatalysts. In this study, CoNi-layered double hydroxide was synthesized using zeolitic imidazolate frameworks-67 as a template, followed by calcination to form CoS2/NiS2. Subsequently, ReS2 was deposited onto the surface of CoS2/NiS2, resulting in the ReS2/CoS2/NiS2 photocatalyst demonstrated notable hydrogen evolution activity under visible light, achieving a maximum hydrogen production rate of 40111.8 µmol/g. The construction of the Z-scheme heterojunction was found to facilitate the transfer and separation of photogenerated carriers while extending the lifetime of photogenerated electrons, thereby contributing to the enhancement of photocatalytic activity. This study provides a new approach for the development of sulfide heterojunctions aimed at improving photocatalytic hydrogen production efficiency.

Theoretical design and synthesis of Co30Ni60/CC for high selective methanol oxidation assisted energy-saving hydrogen production.

The integration of methanol oxidation reaction (MOR) with hydrogen evolution reaction (HER) represents an advanced approach to hydrogen production technology. Nonetheless, the rational design and synthesis of bifunctional catalysts for both MOR and HER with exceptional activity, stability and selectivity present formidable challenges. In this work, firstly, density functional theory (DFT) was utilized to design and evaluate material models with high performance for both MOR and HER. Secondly, guided by DFT, Co30Ni60/CC (CC, carbon cloth) composites with a leaf-like nanosheet structure were successfully fabricated via electrodeposition. In the MOR process, Ni acts as the predominant active center, while Co amplifies the electrochemically active surface area (ECSA) and enhances the selectivity of methanol oxidation. Conversely, in the HER process, Co serves as the primary active center, with Ni augmenting the charge transfer rate. The electrochemical results demonstrate that Co30Ni60/CC exhibits exceptional performance in both MOR and HER at a current density (j) of 10 mA cm-2, with peak potentials of 1.323 V and -95 mV, respectively. Additionally, it shows remarkable selectivity for the oxidiation of methanol to high value-added formic acid. Thirdly, following a 100 h chronopotentiometry (CP) test, the required potential demonstrates an increase of 4.9 % (MOR) and 8.1 % (HER), signifying the superior stability of Co30Ni60/CC compared to those reported in the literature. The exceptional performance of Co30Ni60/CC can be primarily attributed to that the leaf-like nanosheets structure not only exposes a plethora of active sites but also facilitates electrolyte diffusion, the monolithic structure prepared by electrodeposition enhances its stability, and the transfer of electrons from Co to Ni regulates its electronic structure, as corroborated by X-ray photoelectron spectroscopy (XPS) and density of states (DOS) analyses. Finally, at the same j, the voltage required by the Co30Ni60/CC||Co30Ni60/CC electrolytic cell, powered by an electrochemical workstation, is 198 mV lower than that required for alkaline water-splitting. Meanwhile, at higher j (100 mA cm-2), the electrolytic cell exhibits sustained and stable operation for 150 h, enabling high-efficiency hydrogen production and the synthesis of high value-added formic acid.

Direct Hydrogen Production Promoted by Laser-Induced Water Plasma.

Hydrogen, as a clean energy carrier, plays an important role in addressing the current energy and environmental crisis. However, conventional hydrogen production technologies require extreme reaction conditions, such as high temperature, high pressure, and catalysts. Herein, we study the microscopic mechanism of laser-induced water plasma and subsequent H2 production with real-time time-dependent density functional theory simulations and ab initio molecular dynamics simulations. The results demonstrate that intense laser excites liquid water to generate nonequilibrium plasma in a warm-dense state, which constitutes a superior reaction environment. Subsequent annealing leads to the recombination of energetic reactive particles to generate H2, O2, and H2O2 molecules. Annealing rate and laser wavelength are shown to modulate the product ratio, and the energy conversion efficiency can reach ∼9.2% with an annealing rate of 1.0 K/fs. This work reveals the nonequilibrium atomistic mechanisms of hydrogen production from laser-induced water plasma and shows far-reaching implications for the design of optically controllable hydrogen technology.

Partial oxidation of Rh/Ru nanoparticles within carbon nanofibers for high-efficiency hydrazine oxidation-assisted hydrogen generation.

Hydrazine oxidation reaction (HzOR), an alternative to oxygen evolution reaction, effectively mitigates hydrazine pollution while achieving energy-efficient hydrogen production. Herein, partially oxidized Ru/Rh nanoparticles embedded in carbon nanofibers (CNFs) are fabricated as a bifunctional electrocatalyst for hydrogen evolution reaction (HER) and HzOR. The presence of multiple components including metallic Ru and Rh and their oxides provides numerous electrochemically active sites and superior charge transfer properties, thus improving the electrocatalytic performance. Additionally, the confinement of the active components within CNFs further enhances structural stability. Consequently, the optimized electrocatalyst exhibits ultralow overpotentials of 16 mV at 10 mA cm-2 and 176 mV to reach an industry-level current density of 1 A cm-2 for HER, considerably outperforming the benchmark Pt/C catalyst. Furthermore, it shows an outstanding anodic HzOR activity, achieving a small potential of -0.019 V to generate 10 mAcm-2. A two-electrode overall hydrazine splitting (OHzS) cell prepared using the electrocatalyst operates at a compelling voltage that is 1.953 V lower than that of the overall water splitting (OWS) cell at 200 mA cm-2. Furthermore, the OHzS cell achieves a hydrogen production rate of 1.17 mmol h-1, which is 15-fold that of OWS. Additionally, Rh1Ru1Ox-CNFs-350 is used to construct a Zn-hydrazine battery with excellent performance. This study presents an effective system for achieving high-yielding green H2 production with low energy consumption while simultaneously addressing hydrazine pollution.

Synthesis of Ag/Cu decorated 3D self-assembled nanowire TiO2 photocatalyst for hydrogen production: a promising pathway towards sustainable energy generation.

Here, synthesis and characterization of TiO2 with different morphologies along with the cost-effective bimetallic decoration on optimized 3D self-assembled nanowire TiO2 (NWT) photocatalyst (Ag/Cu-NWT) with overwhelming hydrogen production rate is reported. All the photocatalysts were well characterized by different characterization techniques. Initially, the effect of morphology change obtained by changing the NaOH concentration has been studied for TiO2. Morphology obtained at 10 M NaOH solution, i.e., NWT (678 µmol/g), showed better hydrogen production than morphology obtained at 5 M (410 µmol/g), 15 M (210 µmol/g), and 20 M (160 µmol/g) NaOH solutions. Further, with the aim to achieve comparable or better activity low-cost photocatalyst as compared to Pt-TiO2 system, NWT was decorated with various Cu percentages and then with a minimal percentage of Ag on an optimized Cu-NWT photocatalyst. The observed trend for photocatalytic hydrogen production has been found to be P25 TiO2 < NWT < 1.0Cu-NWT < 0.5Pt-NWT ≤ 0.1Ag/1.0Cu-NWT. The marked increase by a factor of 103 in hydrogen production for the optimized bimetallic 0.1Ag/1.0Cu-NWT (10,184 µmol/g) photocatalyst compared to P25 TiO2 (99 µmol/g), nearly threefold increment in hydrogen production than an optimized 1.0 Cu-NWT (3907 µmol/g) photocatalyst and comparable hydrogen production as compared to 0.5Pt-NWT (10,050 µmol/g) may be attributed to the successful synthesis of a highly porous NWT morphology, which offers large surface area, increased light absorption combined with the synergistic effects of surface plasmon resonance (SPR), and the Schottky barrier for H+ reduction to H2 gas. The optimization of TiO2 morphology and an inexpensive bimetallic decoration strategy opens up promising opportunities for the development of cost-effective photocatalysts in the realm of energy and environment.

Supramolecular Reconstruction of Self-Assembling Photosensitizers for Enhanced Photocatalytic Hydrogen Evolution.

Natural photosynthetic systems require spatiotemporal organization to optimize photosensitized reactions and maintain overall efficiency, involving the hierarchical self-assembly of photosynthetic components and their stabilization through synergistic interactions. However, replicating this level of organization is challenging due to the difficulty in efficiently communicating supramolecular nano-assemblies with nanoparticles or biological architectures, owing to their dynamic instability. Herein, we demonstrate that the supramolecular reconstruction of self-assembled amphiphilic rhodamine B nanospheres (RN) through treatment with metal-phenolic coordination complexes results in the formation of a stable hybrid structure. This reconstructed structure enhances electron transfer efficiency, leading to improved photocatalytic performance. Due to the photoluminescence quenching property of RN and its electronic synergy with tannic acid (T) and zirconium (Z), the supramolecular complexes of hybrid nanospheres (RNTxZy) with Pt nanoparticles or a biological workhorse, Shewanella oneidensis MR-1, showed marked improvement in photocatalytic hydrogen production. The supramolecular hybrid particles with a metal-phenolic coordination layer showed 5.6- and 4.0-fold increases, respectively, in the productivities of hydrogen evolution catalyzed by Pt (Pt/RNTxZy) and MR-1 (M/RNTxZy), respectively. These results highlight the potential for further advancements in the structural and photochemical control of supramolecular nanomaterials for energy harvesting and bio-hybrid systems.

ZnO with Different Morphologies Sensitized by Metalloporphyrins as Catalysts for H2 Production by Water Splitting under Sunlight.

In this work, zinc oxide with different morphologies and textural properties were prepared and sensitized with metalloporphyrins (MPs) aiming to improve its solar energy harvesting capability for H2 production by water splitting under sunlight (a 300 W Xe/Hg lamp). An anionic iron(III)porphyrin and a cationic manganese(III)porphyrin were immobilized on different ZnO solids predominantly by electrostatic interactions. In general, the prepared MP-free ZnO solid yielded modest catalytic results which had apparently no direct correlation with their textural properties or morphology. On the other hand, when these ZnO solids had iron or manganese porphyrin sensitizing them, their catalytic performances changed and a superior yield towards H2 production was observed in comparison to the pure ZnO solids, making evident the synergy achieved between these two components (ZnO and metalloporphyrins) for the prepared solids. It was also observed that the metalloporphyrins and the respective free-base ligand suffered redox reactions when used as homogenous catalyst in this reaction, which could influence their performances as catalysts. The same was not observed in the solids containing immobilized MP, suggesting some protective effect of the ZnO solids on the MP complexes upon immobilization probably due to interaction of the complexes with the ZnO matrix.

Multi-Bioinspired Fog Harvesting Structure with Asymmetric Surface for Hydrogen Revolution.

The urgent need for sustainable energy storage drives the fast development of diverse hydrogen production based on clean water resources. Herein, a unique type of multi-bioinspired functional device (MFD) is reported with asymmetric wettability that combines the curvature gradient of cactus spines, the wetting gradient of lotus, and the slippery surface of Nepenthes alata for efficient fog harvesting. The precisely printed MFDs with microscale features, spanning dimensions, and a thin wall are endowed with asymmetric wettability to enable the Janus effects on their surfaces. Fog condenses on the superhydrophobic surface of the MFDs in the form of microdroplets and unidirectionally penetrates its interior due to the Janus effects, and drops onto the designated area with a better fog harvesting rate of 10.64 g cm-2 h-1. Most significantly, the collected clean water can be used for hydrogen production with excellent stability and durability. The findings demonstrate that safe, large-scale, high-performance water splitting and gas separation and collection with fog collection based on MFDs are possible.

Environmental Impact of Waste Treatment and Synchronous Hydrogen Production: Based on Life Cycle Assessment Method.

Based on the life cycle assessment methodology, this study systematically analyzes the energy utilization of environmental waste through photocatalytic treatment and simultaneous hydrogen production. Using 10,000 tons of organic wastewater as the functional unit, the study evaluates the material consumption, energy utilization, and environmental impact potential of the photocatalytic waste synchronous hydrogen production system (specifically, the synchronous hydrogen production process of 4-NP wastewater with CDs/CdS/CNU). The findings indicate that potential environmental impacts from the photochemical treatment of environmental waste and synchronous hydrogen production primarily manifest in freshwater ecological toxicity, marine ecological toxicity, terrestrial ecological toxicity, and non-carcinogenic toxicity to humans. These ecological impacts stem from the catalyst's adsorption and metal leaching during the photo-degradation and hydrogen production processes of environmental waste. By implementing reasonable modifications and morphological refinements to the catalyst, these effects can be mitigated while achieving enhanced efficiency in environmental waste processing and simultaneous hydrogen production. The research outcomes provide valuable insights for advancing sustainable development in green technology for environmental waste treatment and energy utilization.

Microwave-assisted organic acids and green hydrogen production during mixed culture fermentation.

BACKGROUND: The integration of anaerobic digestion into bio-based industries can create synergies that help render anaerobic digestion self-sustaining. Two-stage digesters with separate acidification stages allow for the production of green hydrogen and short-chain fatty acids, which are promising industrial products. Heat shocks can be used to foster the production of these products, the practical applicability of this treatment is often not addressed sufficiently, and the presented work therefore aims to close this gap. METHODS: Batch experiments were conducted in 5 L double-walled tank reactors incubated at 37 °C. Short microwave heat shocks of 25 min duration and exposure times of 5-10 min at 80 °C were performed and compared to oven heat shocks. Pairwise experimental group differences for gas production and chemical parameters were determined using ANOVA and post-hoc tests. High-throughput 16S rRNA gene amplicon sequencing was performed to analyse taxonomic profiles. RESULTS: After heat-shocking the entire seed sludge, the highest hydrogen productivity was observed at a substrate load of 50 g/l with 1.09 mol H2/mol hexose. With 1.01 mol H2/mol hexose, microwave-assisted treatment was not significantly different from oven-based treatments. This study emphasised the better repeatability of heat shocks with microwave-assisted experiments, revealing low variation coefficients averaging 29%. The pre-treatment with microwaves results in a high predictability and a stronger microbial community shift to Clostridia compared to the treatment with the oven. The pre-treatment of heat shocks supported the formation of butyric acid up to 10.8 g/l on average, with a peak of 24.01 g/l at a butyric/acetic acid ratio of 2.0. CONCLUSION: The results support the suitability of using heat shock for the entire seed sludge rather than just a small inoculum, making the process more relevant for industrial applications. The performed microwave-based treatment has proven to be a promising alternative to oven-based treatments, which ultimately may facilitate their implementation into industrial systems. This approach becomes economically sustainable with high-temperature heat pumps with a coefficient of performance (COP) of 4.3.

Boosting the Production of Hydrogen from an Overall Urea Splitting Reaction Using a Tri-Functional Scandium-Cobalt Electrocatalyst.

The creation of highly efficient and economical electrocatalysts is essential to the massive electrolysis of water to produce clean energy. The ability to use urea reaction of oxidation (UOR) in place of the oxygen/hydrogen evolution process (OER/HER) during water splitting is a significant step toward the production of high-purity hydrogen with less energy usage. Empirical evidence suggests that the UOR process consists of two stages. First, the metal sites undergo an electrochemical pre-oxidation reaction, and then the urea molecules on the high-valence metal sites are chemically oxidized. Here, the use of scandium-doped CoTe supported on carbon nanotubes called Sc@CoTe/CNT is reported and CoTe/CNT as a composite to efficiently promote hydrogen generation from highly durable and active electrocatalysts for the OER/UOR/HER in urea and alkali solutions. Electrochemical impedance spectroscopy indicates that the UOR facilitates charge transfer across the interface. Furthermore, the Sc@CoTe/CNT nanocatalyst has high performance in KOH and KOH-containing urea solutions as demonstrated by the HER, OER, and UOR (215 mV, 1.59, and 1.31 V, respectively, at 10 mA cm-2 in 1 m KOH) and CoTe/CNT shows 195 mV, 1.61 and 1.3 V, respectively. Consequently, the total urea splitting system achieves 1.29 V, whereas the overall water splitting device obtaines 1.49 V of Sc@CoTe/CNT and CoTe/CNT shows 1.54, 1.48 V, respectively. This work presents a viable method of combining HER with UOR for maximally effective hydrogen production.

Iridium Single-Atom-Ensembles Stabilized on Mn-Substituted Spinel Oxide for Durable Acidic Water Electrolysis.

Exploring single-atom-catalysts for the acidic oxygen evolution reaction (OER) is of paramount importance for cost-effective hydrogen production via acidic water electrolyzers. However, the limited durability of most single-atom-catalysts and Ir/Ru-based oxides under harsh acidic OER conditions, primarily attributed to excessive lattice oxygen participation resulting in metal-leaching and structural collapse, hinders their practical application. Herein, an innovative strategy is developed to fabricate short-range Ir single-atom-ensembles (IrSAE) stabilized on the surface of Mn-substituted spinel Co3O4 (IrSAE-CMO), which exhibits excellent mass activity and significantly improved durability (degradation-rate: ≈2 mV h-1), outperforming benchmark IrO2 (≈44 mV h-1) and conventional Irsingle-atoms on pristine-Co3O4 for acidic OER. First-principle calculations reveal that Mn-substitution in the octahedral sites of Co3O4 substantially reduces the migration energy barrier for Irsingle-atoms on the CMO surface compared to pristine-Co3O4, facilitating the migration of Irsingle-atoms to form strongly correlated IrSAE during pyrolysis. Extensive ex situ characterization, operando X-ray absorption and Raman spectroscopies, pH-dependence activity tests, and theoretical calculations indicate that the rigid IrSAE with appropriate Ir-Ir distance stabilized on the CMO surface effectively suppresses lattice oxygen participation while promoting direct O─O radical coupling, thereby mitigating Ir-dissolution and structural collapse, boosting the stability in an acidic environment.

General synthesis of single-crystalline Ta2O5 nanorods towards enhanced photocatalytic H2 production activity.

As a potential candidate for photocatalytic H2 production from water splitting, Ta2O5 catalyst presents suitable conduction and valence band positions, but suffers from poor charge transfer ability, which seriously limits its photocatalytic performance enhancement. Here, a facile and eco-friendly hydrothermal method was developed for the fabrication of one-dimensional (1D) Ta2O5 nanorods using the freshly precipitated tantalic acids as the precursors. An oriented attachment mechanism was proposed for the growth of Ta2O5 nanorods. Moreover, the present synthetic approach was further extended to direct synthesis of nine kinds of alkaline tantalates and alkaline-earth tantalates nanostructures, suggesting its general applicability. A significant increase in activity in photocatalytic H2 production was revealed on 1D Ta2O5 nanorods. The improved photocatalytic H2 production activity of Ta2O5 nanorods was mainly attributed to its 1D nanorods structure with high crystallization and large specific surface areas as well as excellent charge transfer efficiency.

Dynamic Reconstruction of Yttrium Oxide-Stabilized Cobalt-Loaded Carbon-Based Catalysts During Thermal Ammonia Decomposition.

Hydrogen production from the decomposition of ammonia is considered an effective approach for addressing challenges associated with hydrogen storage and transportation. However, their relatively high energy consumption and low efficiency hinder practical multi-scenario applications. In this study, Y2O3-stabilized catalysts with Co-loaded onto porous nitrogen-doped carbon (Y2O3-Co/NC) are synthesized by pyrolysis of Y(NO3)3-modified ZIF-67 under an inert atmosphere, followed by annealing in a reducing environment. The introduction of Y2O3 enhanced the recombination and desorption of N atoms and facilitated the gradual dehydrogenation of NHx on the catalyst surface, resulting in improved catalytic activity for the thermal decomposition of ammonia. Benefitting from the electron-donating properties of Y2O3 and N-doped carbon, the optimized catalyst achieved a remarkable NH3 conversion efficiency of 92.3% at a high gas hourly space velocity of 20 000 cm3· g cat - 1 ${\mathrm{g}}_{{\mathrm{cat}}}^{ - {\mathrm{1}}}$ ·h-1 with an encouraging H2 production rate of 20.6 mmol· g cat - 1 ${\mathrm{g}}_{{\mathrm{cat}}}^{ - {\mathrm{1}}}$ ·min-1 at 550 °C. Moreover, the synthesized catalyst undergoes a fast-dynamic reconstruction process, resulting in exceptionally stable catalytic activity during the thermal decomposition of ammonia, rendering it a promising candidate for carbon-free energy thermocatalytic conversion technology.

Tuning Electronic and Proton Transfer Properties on Amino-Functionalized Co-Based MOF for Efficient Photocatalytic Hydrogen Evolution.

Efficient hydrogen (H2) production through photocatalytic water splitting was achieved by using an amino-functionalized azolate/cobalt-based metal-organic framework (MOF). While previous reports highlighted the amino group's role only as a substituent group for enabling light absorption of MOFs in the visible region, our present study revealed its dual role. The amino substituent not only acts as an electron donor to increase the electron availability at the active Co sites but also provides hydrogen-hopping sites within the pore channel, facilitating proton (H+) diffusion along the framework. This dual functionality significantly boosts the performance of this Co-MOF as a hydrogen evolution cocatalyst. When combined with fluorescein and triethylamine as the photosensitizer and sacrificial agent, respectively, the Co-MOF achieved a remarkable H2 production rate of 27 mmol g-1 over 4 h. Notably, this performance surpasses those of benchmark platinum (Pt) and titanium dioxide (TiO2) cocatalysts.