Catalysts For Hydrogen Production Research Articles

Tuning Binding Strength of Multiple Intermediates towards Efficient pH‐universal Electrocatalytic Hydrogen Evolution by Mo8O26‐NbNxOy Heterocatalysts

AbstractDeveloping efficient and robust hydrogen evolution reaction (HER) catalysts for scalable and sustainable hydrogen production through electrochemical water splitting is strategic and challenging. Herein, heterogeneous Mo8O26‐NbNxOy supported on N‐doped graphene (defined as Mo8O26‐NbNxOy/NG) is synthesized by controllable hydrothermal reaction and nitridation process. The O‐exposed Mo8O26 clusters covalently confined on NbNxOy nanodomains provide a distinctive interface configuration and appropriate electronic structure, where fully exposed multiple active sites give excellent HER performance beyond commercial Pt/C catalyst in pH‐universal electrolytes. Theoretical studies reveal that the Mo8O26‐NbNxOy interface with electronic reconstruction affords near‐optimal hydrogen adsorption energy and enhanced initial H2O adsorption. Furthermore, the terminal O atoms in Mo8O26 clusters cooperate with Nb atoms to promote the initial H2O adsorption, and subsequently reduce the H2O dissociation energy, accelerating the entire HER kinetics.

Tuning Binding Strength of Multiple Intermediates towards Efficient pH-universal Electrocatalytic Hydrogen Evolution by Mo8 O26 -NbNx Oy Heterocatalysts.

Developing efficient and robust hydrogen evolution reaction (HER) catalysts for scalable and sustainable hydrogen production through electrochemical water splitting is strategic and challenging. Herein, heterogeneous Mo8 O26 -NbNx Oy supported on N-doped graphene (defined as Mo8 O26 -NbNx Oy /NG) is synthesized by controllable hydrothermal reaction and nitridation process. The O-exposed Mo8 O26 clusters covalently confined on NbNx Oy nanodomains provide a distinctive interface configuration and appropriate electronic structure, where fully exposed multiple active sites give excellent HER performance beyond commercial Pt/C catalyst in pH-universal electrolytes. Theoretical studies reveal that the Mo8 O26 -NbNx Oy interface with electronic reconstruction affords near-optimal hydrogen adsorption energy and enhanced initial H2 O adsorption. Furthermore, the terminal O atoms in Mo8 O26 clusters cooperate with Nb atoms to promote the initial H2 O adsorption, and subsequently reduce the H2 O dissociation energy, accelerating the entire HER kinetics.

Photoredox Cascade Catalyst for Efficient Hydrogen Production with Biomass Photoreforming.

Biomass photoreforming is a promising method to provide both a clean energy resource in the form of hydrogen (H2 ) and valuable chemicals as the results of water reduction and biomass oxidation. To overcome the poor contact between heterogeneous photocatalysts and biomass substrates, we fabricated a new photoredox cascade catalyst by combining a homogeneous catalyst, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), and a heterogeneous dual-dye sensitized photocatalyst (DDSP) composed of two Ru(II)-polypyridine photosensitizers (RuP6 and RuCP6 ) and Pt-loaded TiO2 nanoparticles. During blue-light irradiation (λ=460±15 nm; 80 mW), the DDSP photocatalytically reduced aqueous protons to form H2 and simultaneously oxidized TEMPO• radicals to generate catalytically active TEMPO+ . It oxidized biomass substrates (water-soluble glycerol and insoluble cellulose) to regenerate TEMPO• . In the presence of N-methyl imidazole as a proton transfer mediator, the photocatalytic H2 production activities for glycerol and cellulose reforming reached 2670 and 1590 μmol H2 (gTiO2 )-1 h-1 , respectively, which were comparable to those of state-of-the-art heterogeneous photocatalysts.

Photoredox Cascade Catalyst for Efficient Hydrogen Production with Biomass Photoreforming

AbstractBiomass photoreforming is a promising method to provide both a clean energy resource in the form of hydrogen (H2) and valuable chemicals as the results of water reduction and biomass oxidation. To overcome the poor contact between heterogeneous photocatalysts and biomass substrates, we fabricated a new photoredox cascade catalyst by combining a homogeneous catalyst, 2,2,6,6‐tetramethylpiperidine 1‐oxyl (TEMPO), and a heterogeneous dual‐dye sensitized photocatalyst (DDSP) composed of two Ru(II)‐polypyridine photosensitizers (RuP6 and RuCP6) and Pt‐loaded TiO2 nanoparticles. During blue‐light irradiation (λ=460±15 nm; 80 mW), the DDSP photocatalytically reduced aqueous protons to form H2 and simultaneously oxidized TEMPO• radicals to generate catalytically active TEMPO+. It oxidized biomass substrates (water‐soluble glycerol and insoluble cellulose) to regenerate TEMPO•. In the presence of N‐methyl imidazole as a proton transfer mediator, the photocatalytic H2 production activities for glycerol and cellulose reforming reached 2670 and 1590 μmol H2 (gTiO2)−1 h−1, respectively, which were comparable to those of state‐of‐the‐art heterogeneous photocatalysts.

Enhancing Oxygen Evolution Reaction Performance in Prussian Blue Analogues: Triple-Play of Metal Exsolution, Hollow Interiors, And Anionic Regulation.

Prussian blue analogs (PBAs) are promising catalysts for green hydrogen production. However, the rational design of high-performing PBAs is challenging, which requires an in-depth understanding of catalytic mechanism. Here FeMn@CoNi core-shell PBAs were employed as precursors, together with Se powders, in low-temperature pyrolysis in an argon atmosphere. This synthesis method enabled the partial dissociation of inner FeMn PBAs that resulted in hollow interiors, Ni nanoparticles (NPs) exsolution to the surface, and Se incorporation onto the PBA shell. The resulting material presented ultra-low oxygen evolution reaction (OER) overpotential (184mV at 10mA cm-2 ) and low Tafel slope (43.4mV dec-1 ), outperforming leading-edge PBA-based electrocatalysts. The mechanism responsible for such a high OER activity was revealed, assisted by DFT calculations and the surface examination before and after the OER process.The exsolved Ni NPs were found to help turn the PBAs into Se-doped core-shell metal oxyhydroxides during the OER, in which the heterojunction with Ni and the Se incorporation were combined to improve the OER kinetics. This work shows that efficient OER catalysts could be developed by using a novel synthesis method backed up by a sound understanding and control of the catalytic pathway. This article is protected by copyright. All rights reserved.

A Mini-Review on Lanthanum–Nickel-Based Perovskite-Derived Catalysts for Hydrogen Production via the Dry Reforming of Methane (DRM)

Given that the attempts to head toward a hydrogen economy are gathering pace, the dry reforming of methane (DRM) to produce hydrogen-rich syngas is a reaction that is worthy of investigation. Nickel-based catalysts have been extensively examined as a cost-effective solution for DRM, though they suffer from fast deactivation caused by coke accumulation. However, a number of published studies report high catalytic performance in terms of both activity and stability for La–Ni-based perovskite-derived catalysts used in DRM in comparison to other corresponding materials. In the work presented herein, a thorough analysis regarding the application of La–Ni-based perovskite catalysts for DRM is carried out. LaNiO3 is known for its anti-coking ability owing to the strong interaction between CO2 and La2O3. A further modification to improve the catalytic performance can be achieved by the partial or complete substitution of A or/and B sites of the perovskite catalysts. The latest developments with respect to this topic are also discussed in this manuscript. Even though the low surface area of perovskite catalysts has always been an obstacle for their commercialization, new supported and porous perovskite materials have recently emerged to address, at least partly, the challenge. Finally, conclusions and future outlooks for developing novel perovskite catalysts that may potentially pioneer new technology are included.

Role of support bio-templating in Ni/Al2O3 catalysts for hydrogen production via dry reforming of methane

Bio-templating, a synthetic approach inspired by nature, is an emerging area in material engineering. In this study, waste leaves of Sycamore were utilized as a bio-template for producing alumina support to prepare catalyst. The performance of Ni and Ce impregnated on bio-templated alumina support was investigated in dry reforming of methane for the first time. The effect of process and catalytic variables were examined in detail. The results showed that impregnation of 20% Ni and 3% Ce on the bio-templated alumina led to improved Ni dispersion and achieving the maximum CH4 conversion of 88.7%, CO2 conversion of 78.5%, and H2 yield of 85.3%, compared to 84.4%, 75.6% and 83.4% for the non-templated catalyst at 700 °C, respectively. Detailed characterization of the catalysts revealed that the enhanced performance in the bio-templated catalyst could be attributed to smaller Ni particles, superior dispersion of Ni on the support, the mesoporous structure of alumina, and the larger surface area of support. Furthermore, analysis of the used catalyst showed reduced coke formation on the catalyst surface and high stability of bio-templated catalysts, highlighting the main advantage of bio-templated catalysts over non-templated ones. The findings presented in this study contribute to the potential future applications of bio-templating materials and shed light on the rational design of bio-templating materials.

Study on the laws of methanol reforming coupled with flow, heat and mass transfer processes with variable catalyst distribution in microchannels

Reactions in microchannel reforming reactors are related to flow and heat/mass transfer, which have an important impact on hydrogen production efficiency. In this paper, a strategy to improve methanol conversion and reduce catalyst cost is obtained by using forced unsteady-state operation, i.e., adopting a catalyst variable-activity arrangement, and by means of experiments and numerical simulations to analyze the mechanism of the enhanced reaction in this way from the perspective of coupled flow and heat-mass transfer. The results demonstrate that the two-section arrangement schemes can increase the Le number and enhance the thermal diffusion. And the “low-high” scheme can make the wall temperature more uniform. In the three-stage arrangement scheme, the methanol conversion rate of “low-high-low” can reach 89.6%. From the second stage onward, the effect of heat mass transfer on the chemical reaction is more significant. Secondly, the interrupted catalyst arrangement effectively improves the heat and mass transfer in the reactor. The methanol conversion was significantly improved by dividing the reactor into four sections, and the best arrangement was “low-none-high-low”, which could achieve 91.2% conversion. The catalyst arrangement of “low-none-low-none” is the most effective solution in terms of hydrogen production performance and catalyst cost.

Enhanced Metal-Support Interactions Boost the Electrocatalytic Water Splitting of Supported Ruthenium Nanoparticles on a Ni3N/NiO Heterojunction at Industrial CurrentDensity.

Developing highly efficient and stable hydrogen production catalysts for electrochemical water splitting (EWS) at industrial current densities remains a great challenge. Herein, we proposed a heterostructure-induced-strategy to optimize the metal-support interaction (MSI) and the EWS activity of Ru-Ni3N/NiO. Density function theory (DFT) calculations firstly predicted that the Ni3N/NiO-heterostructures can improve the structural stability, electronic distributions, and orbital coupling of Ru-Ni3N/NiO, compared to Ru-Ni3N and Ru-NiO, which accordingly decreases energy barriers and increases the electroactivity for EWS. As a proof-of-concept, the Ru-Ni3N/NiO catalyst with 2D Ni3N/NiO-heterostructures nanosheet array, uniformly dispersed Ru nanoparticles, and strong MSI, was successfully constructed in the experiment, which owns an excellent HER and OER activity with overpotentials of 190 mV and 385 mV at 1000 mA cm-2, respectively. Furthermore, the Ru-Ni3N/NiO-based EWS device can realize an industrial current density (1000 mA cm-2) at 1.74 V and 1.80 V under alkaline pure water and seawater conditions, respectively. Additionally, it also achieves a high durability of 1000 h (@ 500 mA cm-2) in alkaline pure water.

Enhanced Metal‐Support Interactions Boost the Electrocatalytic Water Splitting of Supported Ruthenium Nanoparticles on a Ni3N/NiO Heterojunction at Industrial Current Density

AbstractDeveloping highly efficient and stable hydrogen production catalysts for electrochemical water splitting (EWS) at industrial current densities remains a great challenge. Herein, we proposed a heterostructure‐induced‐strategy to optimize the metal‐support interaction (MSI) and the EWS activity of Ru‐Ni3N/NiO. Density functional theory (DFT) calculations firstly predicted that the Ni3N/NiO‐heterostructures can improve the structural stability, electronic distributions, and orbital coupling of Ru‐Ni3N/NiO compared to Ru‐Ni3N and Ru‐NiO, which accordingly decreases energy barriers and increases the electroactivity for EWS. As a proof‐of‐concept, the Ru‐Ni3N/NiO catalyst with a 2D Ni3N/NiO‐heterostructures nanosheet array, uniformly dispersed Ru nanoparticles, and strong MSI, was successfully constructed in the experiment, which exhibited excellent HER and OER activity with overpotentials of 190 mV and 385 mV at 1000 mA cm−2, respectively. Furthermore, the Ru‐Ni3N/NiO‐based EWS device can realize an industrial current density (1000 mA cm−2) at 1.74 V and 1.80 V under alkaline pure water and seawater conditions, respectively. Additionally, it also achieves a high durability of 1000 h (@ 500 mA cm−2) in alkaline pure water.

Scalable room-temperature synthesis of NiFe oxyhydroxide tailored with S atoms for enhanced oxygen evolution in alkaline seawater and domestic sewage

Developing facile and scalable method to prepare oxygen evolution reaction (OER) catalysts which is suitable for industrial water electrolysis at large operating current densities is vital for green hydrogen production, but still remains a great challenge. Herein, we developed a one-step method to in situ fabricate S-doped NiFe oxyhydroxide (S–Ni(Fe)OOH) ultrathin nanosheet on Ni foam at room temperature, which is suitable for scaled up production, by which a electrode with 500 cm2 can be facilely prepared. The prepared S–Ni(Fe)OOH shows excellent OER stability and activity in 5 M KOH, alkaline sewage and seawater, which only need 198, 275 and 284 mV to reach 500 mA cm−2, respectively. Theoretical calculations indicated that the incorporation of S modulates the chemisorption of oxygen-containing intermediates and facilitates the evolution from ∗OH to ∗O, thus enhance the intrinsic OER activity of S–Ni(Fe)OOH. The electrolyzer based on S–Ni(Fe)OOH can reach a current density of 100 mA cm−2 at a small cell voltage of 1.56 V in 1 M KOH, much smaller than the benchmark catalyst Pt/C||IrO2(1.87 V). This work provides a facile method to prepare highly efficient catalyst for alkaline sewage and seawater oxidation, which could provide references to the development of catalyst for practical hydrogen production.

Metal-Free Coal Catalyst for Hydrogen Production: Synthesis and Performance Assessment

In this study, a coal-based catalyst produced by protonating phosphoric acid was used as a metal-free catalyst for hydrogen production from sodium borohydride (NaBH4) methanolysis. Experiments were conducted with various acid concentrations, impregnation times, and carbonization temperatures and times in order to produce a metal-free coal catalyst with enhanced catalytic activity. The catalyst impregnated with 3M H3PO4 for 12 h and subsequently carbonized at 600°C for 90 min exhibited the highest catalytic activity. The hydrogen production at 60 °C methanolysis with 0.25 g of NaBH4 catalyzed by a metal-free coal catalyst was found to be 11,854 mL min−1g.cat−1. Additionally, the activation energy of the catalyst was determined to be 22.5 kJ mol-1.

In situ synthesis of C–SiO2 enhanced Pd nanoparticles for catalytic dehydrogenation of formic acid

Formic acid (FA, HCOOH), as a liquid chemical hydrogen storage carrier with low cost, high hydrogen content, and convenient storage and transportation, has attracted extensive attention. Pd-based catalysts for hydrogen production from FA are easy to aggregate and deactivate in the reaction process, which hinders the further development of FA as a hydrogen storage carrier. Therefore, the exploitation of carriers with simple preparation methods and excellent performance can effectively improve the catalytic activity of Pd-based catalysts. Porous carbon and SiO2 have been widely used for their unique structural properties, and the preparation of composite carriers by combining the advantages of both is a current research hotspot. Herein, this work synthesized C–SiO2 for the deposition of Pd nanoparticles by a one-step method, and the obtained Pd/C–SiO2 exhibits a superior FA dehydrogenation activity with a turnover frequency value of 1278 h−1 and a favorable stability with only a slight decrease in activity after five cycles.

High temperature shock synthesis of superfine Ru nanoparticles anchored on TiO2 @nitrogen-doped carbon for pH-universal hydrogen evolution reaction

Due to energy crisis and environmental pollution, it is urgent to develop efficient and cheap catalysts for hydrogen production from water electrolysis. As a cheaper platinum group metal, Ru, a cheaper platinum group metal, is a highly competitive candidate to Pt because of the similar bond energy of M-H. Herein, TiO2 @nitrogen-doped carbon composite supported superfine Ru nanoparticles was synthesized by high temperature shock in a Joule furnace using Ti-MOF support (Ru/TiO2 @NC-J). In the extremely rapid process, MOF was quickly converted into highly conductive nitrogen-doped carbon with tiny TiO2 dispersed in it, and superfine Ru nanoparticles were generated simultaneously in less than 0.5 s. The obtained Ru/TiO2 @NC-J displays wonderful HER performance in the wide pH range. In 1.0 M KOH solution, the overpotential was as low as 11 mV at 10 mA cm−2 and a Tafel slope was 39.2 mV dec−1, which far exceeded the activity of Pt/C and conventional calcined samples as well as most of the recently reported catalysts. The as-developed electrocatalysts also showed excellent stability to accommodate large working current for long term test without obvious activity loss in universal pH range. Experimental investigations suggest that the strong metal-support interaction dominantly facilitate the activity of electrocatalytic hydrogen evolution reaction (HER), and stability of Ru/TiO2 @NC-J. This strategy provides a new and super-fast methodology to prepare low-budget and high-performance HER catalysts for practical applications.

Overview of Ni-Based Catalysts for Hydrogen Production from Biogas Reforming

The environmental impact and the forecasted scarcity of fossil fuels have intensified research on renewable energy sources. Hydrogen is a versatile energy carrier that can be produced from renewable sources and plays a key role in achieving global decarbonization targets. Biogas, produced by anaerobic digestion of organic compounds, is rich in methane and carbon dioxide and can be used to produce renewable hydrogen by dry reforming. This review focuses on the recent advances in Ni-based catalysts for biogas reforming. The effect of supports and promoters on catalyst activity, stability, and resistance to carbon deposition will be systematically discussed. This review provides a better understanding of the influence of the synthesis method, metal-support interaction, acid/base sites, and oxygen mobility on catalytic activity. Special emphasis will be given to the development of core-shell structure catalysts and bimetallic catalysts of Ni with other transition metals and noble metals.

Two-dimensional MoSe2/PtSe2 van der Waals type-II heterostructure: Promising visible light photocatalyst for overall water splitting

The development of simple and efficient visible light photocatalytic catalysts for hydrogen production from water is an important development direction in the field of photocatalysis, and composite two-dimensional materials are found to be promising candidates. This paper constructs a novel two-dimensional MoSe2/PtSe2 type-II heterojunction and systematically studies its geometric structure, electronic structure, and optical properties by first-principles calculation. It is evident that the heterojunction has good thermodynamic, kinetic, and mechanical stability, as well as excellent hole carrier mobility, which is conducive to the separation of photogenerated electrons and holes. The optical properties show that MoSe2/PtSe2 heterojunction has the best optical absorption efficiency for visible light and has the ability to cross the water-cracking oxidation-reduction potential at pH = 4. More importantly, the MoSe2/PtSe2 heterojunction shows great hydrogen absorption reaction performance, indicating that it is a potential photocatalyst for overall water splitting of visible light, and has broad application prospects in the field of photocatalysis and optoelectronics.

Hexagonal Defect‐Rich MnOx/RuO2 with Abundant Heterointerface to Modulate Electronic Structure for Acidic Oxygen Evolution Reaction

AbstractDeveloping green hydrogen energy to power future societies has driven the progress of proton‐exchange membrane water electrolyzers (PEMWE). However, due to the complex anode oxygen evolution reaction (OER) electron transfer process and the strong acidic environment, the most effective catalysts are still Ir‐based nanomaterials. Therefore, exploiting low cost acidic OER catalysts to meet the needs of PEMWE remains a challenging and rewarding task. Herein, hexagonal‐shaped and defect‐rich MnOx/RuO2 heterojunction nanosheets (H/d‐MnOx/RuO2) is designed. The oxygen vacancies and heterogeneous structure enable the H/d‐MnOx/RuO2 catalyst to reach 10 mA cm−2 with only overpotential 178 mV in 0.5 m H2SO4. Density functional theory shows that the oxygen vacancies and heterogeneous interface facilitates the reduction of the adsorption energy of *OOH and the reduction of the energy level of Ru‐Oads, thus suppressing the involvement of lattice oxygen and enhancing the durability. This study provides an effective way to design efficient catalysts for hydrogen production in PEMWE.

Revisited Catalytic Hydrogen Evolution Reaction Mechanism of MoS2.

MoS2 has long been considered a promising catalyst for hydrogen production. At present, there are many strategies to further improve its catalytic performance, such as edge engineering, defect engineering, phase engineering, and so on. However, at present, there is still a great deal of controversy about the mechanism of MoS2 catalytic hydrogen production. For example, it is generally believed that the base plane of MoS2 is inert; however, it has been reported that the inert base plane can undergo a transient phase transition in the catalytic process to play the catalytic role, which is contrary to the common understanding that the catalytic activity only occurs at the edge. Therefore, it is necessary to further understand the mechanism of MoS2 catalytic hydrogen production. In this article, we summarized the latest research progress on the catalytic hydrogen production of MoS2, which is of great significance for revisiting the mechanism of MoS2 catalytic hydrogen production.

Investigating Periodic Table Interpolation for the Rational Design of Nanoalloy Catalysts for Green Hydrogen Production from Ammonia Decomposition

Developing highly active catalysts for the decomposition of ammonia to produce hydrogen is an important goal in the context of renewable energy. Allied with this is a need for identification strategies to efficiently design novel catalysts integral to ensuring rapid progress in this research field. We investigated the efficacy of N–binding energy and periodic table interpolation to predict active bimetallic nanoparticle catalysts. Supported iron-platinum and iron-palladium were identified and experimentally shown to be more active than their monometallic analogues. Atomic resolution electron microscopy indicated that the most active catalyst (5 wt% Fe80Pt20/γ-Al2O3) was principally formed of alloyed nanoparticles. It restructured during testing, yet no activity loss was noted at 20 h time-on-line. While these findings show that periodic table interpolation may be a viable tool for identifying active combinations of metals, the activity of the catalysts in the current work were not able to outperform the Ru/Al2O3 benchmark. Further catalyst optimization or refinement of reaction descriptors may facilitate the development of catalysts with higher intrinsic activity than the current state-of-the-art catalysts.Graphical

Synergistic Promotion of Large-Current Water Splitting through Interfacial Engineering of Hierarchically Structured CoP-FeP Nanosheets with Rich P Vacancies.

The development of hydrogen evolution reaction (HER) catalysts with high performance under large current density is still a challenge. Introducing P vacancies in heterostructure is an appealing strategy to enhance HER kinetics. This study investigates a CoP-FeP heterostructure catalyst with abundant P vacancies (Vp-CoP-FeP/NF) on nickel foam (NF), which was prepared using dipping and phosphating treatment. The optimized Vp-CoP-FeP catalyst exerted prominent HER catalytic capability, requiring an ultra-low overpotential (58 mV @ 10 mA cm-2 ) and displaying robust durability (50 h @ 200 mA cm-2 ) in 1.0 M KOH solution. Furthermore, the catalyst demonstrated superior overall water splitting activity as cathode, demanding only cell voltage of 1.76 V at 200 mA cm-2 , outperforming Pt/C/NF(-) || RuO2 /NF(+) . The catalyst's outstanding performance can be attributed to the hierarchical structure of porous nanosheets, abundant P vacancies, and synergistic effect between CoP and FeP components, which promote water dissociation and H* adsorption and desorption, thereby synergically accelerating HER kinetics and enhancing HER activity. This study demonstrates the potential of HER catalysts with phosphorus-rich vacancies that can work under industrial-scale current density, highlighting the importance of developing durable and efficient catalysts for hydrogen production.