Hydrogen Evolution Activity Research Articles

Enhanced Photocatalytic Hydrogen Evolution Activity Driven by the Synergy Between Surface Vacancies and Cocatalysts: Surface Reaction Matters.

The incorporation of defects and cocatalysts is known to be effective in improving photocatalytic activity, yet their coupled contribution to the photocatalytic hydrogen evolution process has not been well-explored. In this study, We demonstrate that the incorporation of S vacancies and NiSe can contribute to the improvement of charge separation efficiency via the formation of a strong electric field within the bulk ZnIn2S4 (ZIS) and on its surface. More importantly, We also demonstrate that the synergy of S vacancies and NiSe benefits the overall hydrogen evolution activity by facilitating the H2O adsorption and dissociation process. This is particularly important for hydrogen evolution taking place under alkaline conditions where the proton concentration is low, allowing ZISv-NiSe (containing abundant S vacancies) to outperform ZIS-NiSe under alkaline conditions. In contrast, under acid conditions, since there are already sufficient amounts of protons available for reaction, the hydrogen evolution activity became governed by the hydrogen adsorption/desorption process rather than the H2O dissociation process. This leads to ZIS-NiSe exhibiting higher activity than ZISv-NiSe due to its more favorable hydrogen adsorption energy. The findings thus provide insights into how defect and cocatalyst modification strategies can be tailor-made to improve hydrogen evolution activity under different pH conditions.

Thiacalix[4]arene-Stabilized Sb/Ag Bimetallic Nanoclusters: Elucidating the Effects of Sb Doping on Electrocatalytic CO2 Reduction in Ag Clusters.

Accurately identifying the metal doping effects within heterogeneous catalysts presents a formidable challenge due to the complex nature of controlling the interfacial chemistry at the molecular level. Herein, we use two sets of atomically precise nanoclusters to demonstrate the impact of Sb doping on the electrocatalytic CO2 reduction activity in Ag nanoclusters. Leveraging the unique properties of the thiacalix[4]arene, we have pioneered a methodology for incorporating catalytic Ag1+ and Sb3+ sites, culminating in the synthesis of the pioneering Sb-Ag bimetallic cluster, Sb2Ag11. We refined this structure by replacing the two Sb3+ sites with Na+ sites, resulting in a Na2Ag10 cluster. Broadening our investigative scope, we isolated the core components from both Sb2Ag11 and Na2Ag10 and obtained two clusters: Sb2Ag4 and Ag4. The subtle compositional variations between two pairs of structurally analogous clusters, Sb2Ag11 and Na2Ag10, as well as Sb2Ag4 and Ag4, create opportunities to investigate how the Sb doping impacts the catalytic activity of Ag clusters. Clearly, compared to the undoped clusters, those doped with Sb exhibit higher catalytic current densities and enhanced CO selectivity. The theoretical calculations suggest that Sb doping can enhance the adsorption barrier of *H, thereby inhibiting hydrogen evolution activity and conversely promoting eCO2RR to CO activity.

0D/2D S-scheme heterojunction of cadmium selenide and covalent triazine frameworks with enhanced photocatalytic activity for hydrogen evolution, carbon dioxide reduction and terpene dehydrogenation

The step-scheme (S-scheme) heterojunction shows the merits of controlling the directional transfer of photogenerated charge carriers and realizing a strong redox potential for photocatalytic hydrogen evolution and carbon dioxide reduction. In this paper, a zero/two-dimensional (0D/2D) S-scheme heterojunction composed of cadmium selenide quantum dots and covalent triazine frameworks (CdSe/CTF) is designed and fabricated by an electrostatic self-assembly approach. Compared with pristine CTF and CdSe quantum dots, the photocatalytic activities of CdSe/CTF composites for hydrogen evolution, carbon dioxide reduction and terpene oxidation are significantly enhanced. The hydrogen evolution rate of CdSe/CTF hybrid photocatalyst immobilized with platinum nanoparticles as cocatalyst reached 19.0 mmol g−1 h−1 under visible-light irradiation, and the apparent quantum yield is 9.8 % at 420 nm. The CdSe/CTF hybrid also exhibited more superior photocatalytic activity in carbon dioxide reduction with a carbon monoxide evolution rate of 1.48 mmol g−1 h−1, and presented higher photocatalytic reactivity in the selective oxidation of α-terpinene to p-cymene. The remarkable enhancement of photocatalytic performance for CdSe/CTF composite is mainly attributed to the facilitated separation and transfer of photoexcited charge carriers of 0D/2D S-scheme heterojunction. This work provides an in-depth insight of utilizing semiconducting polymers as a suitable platform to sustainably transform inexhaustive solar energy to storable chemical energy.

Hydrogen Evolution Activity of Platinum Nanoparticles Decorated on Silver Nanowire Networks and Graphite Electrodes

The catalytic activity of graphite (C) and conductive silver nanowire (AgNW) networks coated on glass and graphite substrates with low platinum content towards hydrogen evolution reaction (HER) is reported. The results exhibit that the chronoamperometric electrodeposition of platinum on AgNW substrates results in the formation of spherically shaped nanoparticle agglomerates aligned on the nanowires. Also, platinum doped graphite electrodes with a rough surface showed an efficient distribution of platinum nanoparticles (PtNPs). Studies of the electrocatalytic HER activity as a function of platinum loading indicate that the optimum loading is in the range of 60 µg/cm2 and further loading results only in a minor reduction of the overpotential. At low Pt content, a synergistic effect of the AgNW network in terms of enhancement of the HER performance was observed. Tafel analysis showed that in the low overpotential region, the Volmer reaction was the rate determining step for the graphite based electrodes. The graphite substrate in conductive connection with the nanowires was shown to significantly boost the hydrogen formation rate.

Stabilizing alkaline hydrogen evolution activity of heterogeneous metal-oxide-nitride cathode by dynamic reconstruction and doping engineering

Stabilizing alkaline hydrogen evolution activity of heterogeneous metal-oxide-nitride cathode by dynamic reconstruction and doping engineering

Evaluation of hydrogen evolution activity by bubbles growth rates as descriptor

Evaluation of the electrocatalytic behavior in the high current density region is critical toward the applications in the industrial water electrolysis system. Here, we utilized the bubble growth rate as descriptor for evaluation of hydrogen evolution reaction. Ag electrode was selected as a model electrode. Pressure-controlled cell was used for the evaluation of the bubble behavior under the wider range in the overpotential. Hydrogen bubble evolution behavior was evaluated by video observation under electrochemical potential control. Even in the presence of the complex processes such as nucleation, growth and detachment of the bubbles, the hydrogen evolution behavior is evaluated with respect to the classical Tafel analyses even in high overpotential region. These analyses provide the methods for the rapid screening toward the material discovery of the green hydrogen production in high current density region.

Platinum‐Group Metal High‐Entropy Selenides for the Hydrogen Evolution Reaction

The selenides of platinum‐group metals (PGMs) are emerging as promising catalysts for diverse electrochemical reactions. To date, most studies have focused on single metal or bimetallic systems, whereas the preparation of a high‐entropy (HE) selenide consisting of five or more PGM elements holds the promise to further enhance catalytic performance by introducing abundant active sites with various local coordination environments and electronic structures. Herein, we report for the first time the synthesis of PGM‐based HE‐Selenide (HE‐Se) nanoparticles with a unique amorphous structure. The atomic metal–Se coordination and the presence of short‐range order were thoroughly revealed. It is further shown that the amorphous HE‐Se can be facilely transformed into a single‐phase crystalline HE‐Se with a cubic structure by thermal annealing. Catalytically, the amorphous HE‐Se showed better acidic hydrogen evolution activity over monometallic PGM‐based selenides and the crystalline counterpart, demonstrating the advantages of high‐entropy configuration and amorphous structure. Our findings may pave the way toward the synthesis and property exploration of amorphous PGM‐based selenides with tunable compositions.

Platinum-Group Metal High-Entropy Selenides for the Hydrogen Evolution Reaction.

The selenides of platinum-group metals (PGMs) are emerging as promising catalysts for diverse electrochemical reactions. To date, most studies have focused on single metal or bimetallic systems, whereas the preparation of a high-entropy (HE) selenide consisting of five or more PGM elements holds the promise to further enhance catalytic performance by introducing abundant active sites with various local coordination environments and electronic structures. Herein, we report for the first time the synthesis of PGM-based HE-Selenide (HE-Se) nanoparticles with a unique amorphous structure. The atomic metal-Se coordination and the presence of short-range order were thoroughly revealed. It is further shown that the amorphous HE-Se can be facilely transformed into a single-phase crystalline HE-Se with a cubic structure by thermal annealing. Catalytically, the amorphous HE-Se showed better acidic hydrogen evolution activity over monometallic PGM-based selenides and the crystalline counterpart, demonstrating the advantages of high-entropy configuration and amorphous structure. Our findings may pave the way toward the synthesis and property exploration of amorphous PGM-based selenides with tunable compositions.

1D Lead Bromide Hybrids Directed by Complex Cations: Syntheses, Structures, Optical and Photocatalytic Properties.

This study presents the synthesis, structural characterization, and evaluation of the photocatalytic performance of two novel one-dimensional (1D) lead(II) bromide hybrids, [Co(2,2'-bpy)3][Pb2Br6CH3OH] (1) and [Fe(2,2'-bpy)3][Pb2Br6] (2), synthesized via solvothermal reactions. These compounds incorporate transition metal complex cations as structural directors, contributing to the unique photophysical and photocatalytic properties of the resulting materials. Single-crystal X-ray diffraction analysis reveals that both compounds crystallize in monoclinic space groups with distinct 1D lead bromide chain configurations influenced by the nature of the complex cations. Optical property assessments show band gaps of 3.04 eV and 2.02 eV for compounds 1 and 2, respectively, indicating their potential for visible light absorption. Photocurrent measurements indicate a significantly higher electron-hole separation efficiency in compound 2, correlated with its narrower band gap. Additionally, photocatalytic evaluations demonstrate that while both compounds degrade organic dyes effectively, compound 2 also exhibits notable hydrogen evolution activity under visible light, a property not observed in 1. These findings highlight the role of metal complex cations in tuning the electronic and structural properties of lead(II) bromide hybrids, enhancing their applicability in photocatalytic and optoelectronic devices.

Cd0.9Zn0.1S/NiB Schottky heterojunction for efficient photothermal-assisted photocatalytic hydrogen evolution

Within the theoretical framework of computational prediction, this study introduces a novel tetrapodal Cd0.9Zn0.1S/NiB (CZS/NiB) Schottky heterojunction material, which demonstrates exceptional photothermal effects and remarkable photocatalytic properties. Notably, under visible light irradiation for 3 h, the photocatalytic hydrogen evolution activity of CZS/NiB-3 % surpasses that of pure CZS by a factor of 10.52. This outstanding photocatalytic hydrogen production performance stems from the successful construction of the CZS/NiB-3 % Schottky heterojunction with promoted the separation and transfer of photogenerated charge carriers and excellent photothermal effect. Additionally, the synthesized CZS/NiB exhibits high photostability and cycling stability. The favorable photothermal effect of the synthesized photocatalyst was experimentally validated through infrared thermography technology. Through in-depth computational investigations using density functional theory, the pathways of charge transfer in the Schottky heterojunction are validated. This study provides a feasible strategy for research on photocatalytic water splitting for hydrogen evolution.

Improved Alkaline Hydrogen Evolution Performance of Dealloying Fe75-xCoxSi12.5B12.5 Electrocatalyst.

The electrocatalytic performance of a Fe65Co10Si12.5B12.5 Fe-based compounds toward alkaline hydrogen evolution reaction (HER) is enhanced by dealloying. The dealloying process produced a large number of nanosheets on the surface of NS-Fe65Co10Si12.5B12.5, which greatly increased the specific surface area of the electrode. When the dealloying time is 3 h, the overpotential of NS-Fe65Co10Si12.5B12.5 is only 175.1 mV at 1.0 M KOH and 10 mA cm-2, while under the same conditions, the overpotential of Fe65Co10Si12.5B12.5 is 215 mV, which is reduced. In addition, dealloying treated electrodes also show better HER performance than un-dealloying treated electrodes. With the increase in Co doping amount, the overpotential of the hydrogen evolution reaction decreases, and the hydrogen evolution activity is the best when the addition amount of Co is 10%. This work not only provides a basic understanding of the relationship between surface activity and the dealloying of HER catalysts, but also paves a new way for doping transition metal elements in Fe-based electrocatalysts working in alkaline media.

Strong electron coupling effect of non-precious metal Schottky junctions enhanced square meter level photocatalytic hydrogen evolution

Photocatalytic hydrogen production technology utilizes solar energy to decompose water into hydrogen, helping to alleviate the pressure of energy depletion. Engineering of non-precious metal nanomaterials as cocatalysts can play a significant role in low-cost, sustainable, and large-scale photocatalytic hydrogen production. Herein, MnCdS-Vs/NiCo2S4 (MCSN) Schottky junction nanomaterials with strong electron coupling effect were prepared by a two-step hydrothermal method and successfully applied to a square meter hydrogen evolution device. The optimized MCSN material demonstrated high hydrogen evolution activity of 34.28 mmol g−1 h−1, which is 9.34 and 685.60 times higher than that of pure MnCdS-Vs and NiCo2S4, respectively. More importantly, in a square meter (1 m2) flat-plate reactor, MCSN produced H2 evolution approximately 201 mmol in 5 h, showcasing its potential for large-scale applications. In-situ XPS and DFT calculations demonstrated that MnCdS-Vs interacts with NiCo2S4 to produce a strong electron coupling effect and form a Schottky junction. It promotes the facilitated the directional migration of photogenerated electrons from MnCdS-Vs to NiCo2S4, but also effectively suppressed electron backflow through the Schottky barrier. Furthermore, the abundance of sulfur vacancies enhanced visible light absorption capability, further improving photocatalytic hydrogen evolution performance. This work delves into the role of defect engineering and Schottky junction design in enhancing photocatalytic performance, providing new insights into transitioning photocatalytic hydrogen production technologies from small-scale laboratory experiments to large-scale practical applications.

Ultrafast fabrication of porous NF/Ni for water splitting in alkaline media

In this study, a rapid hydrogen-bubble template electrodeposition method was employed to synthesize a dual-functional catalyst (NF/Ni) for alkaline water splitting. Physical characterization revealed that a coarsened NF/Ni with a porous structure was obtained, providing an enlarged surface area. In addition, it revealed that the CV activation is beneficial to the formation of Ni-Ni(OH)2 coupling interface, which is responsible for reducing of water dislocation energy barrier and providing a balanced H adsorption energy on the Ni site. Consequently, the overpotential of oxygen/hydrogen evolution reaction at 10 mA cm−2 is 290 and 71 mV. In-situ Raman spectroscopies confirm that the generated NiOOH serves as the active center for OER process. When assembled to a two-electrode cell, it showed a cell voltage of 1.62 V@10 mA cm−2, which was 160 mV lower than that of NF‖NF. Furthermore, the university study confirms the formation of hydroxide on the surface of the metal is beneficial to boosting the hydrogen evolution activity.

Strong electron coupling between amorphous WP and MoSe2/ZnCdS S-scheme heterojunction for enhanced wide spectrum photocatalytic hydrogen production

The photogenerated carrier separation efficiency is a key factor for limiting the photocatalytic activity. In this work, an amorphous WP modified S-scheme MoSe2/ZnCdS (WP/MoSe2/ZCS) heterojunction was synthesized for wide spectrum photocatalytic hydrogen production. After initially forming an S-scheme heterojunction by compositing ZnCdS with nano flower-shaped MoSe2, the light absorption ability of the bimetallic sulfide was significantly enhanced, along with an improved photogenerated carrier separation efficiency. Additionally, the introduction of WP as a co-catalyst not only provides more active sites for photocatalytic reactions, but also enhances the photogenerated electrons transfer through the synergistic effect of strong electronic coupling and S-scheme MoSe2/ZCS heterojunction.The significant enhancement of photocatalytic hydrogen evolution activity of 7％WP/MoSe2/ZCS reached 47.7 mmol g−1 h−1, which is 4.72 times higher than that of ZnCdS (10.1 mmol g−1 h−1). The strong electron coupling effects and S-scheme electron ransfer mechanism was proved by in-situ XPS and Density functional theory (DFT) calculations. This work provides a new strategy for the construction of high-efficiency photocatalyst with strong electronic coupling.

IrxCu0.5Ce0.5Ox/C nanocluster bifunctional electrocatalyst has high water splitting performance in acidic electrolyte

As an effective electrocatalyst for water decomposition, precious metals face limitations in widespread use due to their high cost. Incorporating other metals into precious metals to enhance electrocatalytic performance while reducing costs poses significant challenges. Within the realm of precious metals, Ir-based electrocatalysts have demonstrated remarkable catalytic activity for both oxygen evolution (OER) and hydrogen evolution (HER). This paper presents the synthesis of oxide-supported Ir-based catalysts containing Cu and Ce through a straightforward polyol reduction method. These catalysts exhibit notable OER and HER activity in acidic electrolytes. The addition of Ce increases oxygen vacancy, enhancing the catalytic performance of the optimized Ir3Cu0.5Ce0.5Ox/C clusters, surpassing IrO2 in OER with an overpotential of 274 mV at 10 mA cm−2. Moreover, these catalysts demonstrate outstanding performance when utilized as cathodes and anodes in H-type electrolytic cells. Overall, this study represents a significant advancement in the development of novel Ir-based electrocatalysts.

Ultrafine ruthenium-based nanoclusters regulated by a three-phase heterogeneous interface exhibiting superior mass activity for alkaline hydrogen evolution

Platinum-based catalysts are considered the most effective catalysts for the hydrogen evolution reaction (HER) in acidic media; however, they exhibit poor performance in alkaline electrolysis waters, which are currently more commercially developed, due to their sluggish water dissociation ability. Small-sized metal Ru nanoparticles, with metal-hydrogen bond strength close to Pt (approximately 65 kcal/mol) and a relatively lower water dissociation barrier, are considered one of the most promising alternatives to the noble metal Pt for alkaline HER. Based on the above statements, the present study innovatively combines the effective strategies of "heterogeneous interface engineering" and "construction of ultrafine active sites" to develop a highly efficient Ru-based catalyst with a three-phase heterogeneous interface, aiming to form its application in alkaline HER. Characterization analysis and DFT calculations demonstrated that the "Rux-Ni(OH)2NiO" three-phase heterogeneous interface constructed around ultrafine Rux clusters effectively modulated the electronic structure of the overall material and optimized the HER kinetic steps. This catalytic material, Rux@NOH/NO, exhibited outstanding electrocatalytic activity in alkaline HER, requiring only 44.2 mV to drive a current density of 10 mA·cm−2, with excellent long-term stability and extremely low active material loading (1.36 wt%-Ru). Specially, its mass activity reached an impressive 18,897.1 A/gRu at 150 mV, which is 10.2 times higher than that of commercial 20wt% Pt/C. In summary, this study synergistically constructs an ultrafine metal ruthenium-based catalyst based on a three-phase heterogeneous interface using a composite strategy, which provides an effective catalyst system for alkaline HER catalytic reactions and holds significance for the rational construction and design of efficient heterogeneous interface electrocatalysts.

In situ XPS confirms enhanced hydrogen evolution in S-scheme heterojunction Cd0.8Mn0.2S/Cu2WS4 via charge vectorial separation

Solar-driven water splitting for hydrogen production is a vital approach to mitigating the energy crisis and achieving carbon neutrality and peak carbon emissions. Cd0.8Mn0.2S holds significant potential for photocatalytic hydrogen evolution but faces severe challenges due to photogenerated carrier recombination. To address this, we employed ultrasonic self-assembly to tightly couple Cu2WS4 nanosheets with Cd0.8Mn0.2S nanoparticles, forming an S-scheme heterojunction to reduce carrier recombination rates. In this configuration, Cd0.8Mn0.2S acts as the electron acceptor, and Cu2WS4 serves as the electron donor. The Cd0.8Mn0.2S/Cu2WS4 structure creates a closely spaced interface, providing the shortest transfer distance for electron migration. The S-scheme heterojunction strategy effectively suppresses the recombination of photogenerated carriers, promoting vectorial separation. Under 10 W white light irradiation, the Cd0.8Mn0.2S/Cu2WS4 composite photocatalyst exhibited remarkable hydrogen evolution activity, with a hydrogen production rate of 39.83 mmol g−1 h−1. This S-scheme heterojunction strategy lays the foundation for the structural design and large-scale application of high-activity visible-light photocatalysts.

Asymmetric Charge Distribution in One-dimensional Metal-Organic Assemblies to Promote Photocatalytic Hydrogen Evolution.

The local charge distribution of photocatalyst is crucial to the catalytic activity due to its influence on the charge separation process. Herein, we report two one-dimensional Ni-based metal-organic assemblies for efficient photocatalytic hydrogen evolution without using noble-metal cocatalysts. By adjusting the aromatic ring in the center of the tricarboxylic ligand, the photocatalytic hydrogen evolution activity was increased from 1715 to 2652 μmol h-1 g-1. The detailed mechanism study shows that the introduced nitrogen atoms in the ligands of the metal-organic coordination assembly could modulate the local charge distribution, and yielding a significant enhancement of the molecular dipole moment which engenders a propulsive force for the effective separation and transport of photoinduced charge carriers. This work provides insights into the local charge distribution via ligand modulation for enhancing the activity of photocatalysts.

Vertical Conductive Metal-Organic Framework Single-Crystalline Nanowire Arrays for Efficient Electrocatalytic Hydrogen Evolution.

The construction of crystalline metal-organic frameworks with regular architectures supportive of enhanced mass transport and bubble diffusion is imperative for electrocatalytic applications; however, this poses a formidable challenge. Here, a method is presented that confines the growth of nano-architectures to the liquid-liquid interface. Using this method, vertically oriented single crystalline nanowire arrays of an Ag-benzenehexathiol (BHT) conductive metal-organic framework (MOF) are fabricated via an "in-plane self-limiting and out-of-plane epitaxial growth" mechanism. This material has excellent electrocatalytic features, including highly exposed active sites, intrinsically high electrical conductivity, and superhydrophilic and superaerophobic properties. Leveraging these advantages, the carefully designed material demonstrates superior electrocatalytic hydrogen evolution activity, resulting in a low Tafel slope of 66mVdec-1 and a low overpotential of 275mV at a high current density of 1Acm-2. Finite element analysis (FEA) and in situ microscopic verification indicates that the nanowire array structure significantly enhances the electrolyte transport kinetics and promotes the rapid release of gas bubbles. The findings highlight the potential of using MOF-based ordered nanoarray structures for advanced electrocatalytic applications.

Two nickel-added poly(polyoxometalate)s built of Keggin-type {Ni6PW9} and Anderson-type NiW6O24via WO4/Sb2O bridges and Ni-O-W linkages with efficient hydrogen evolution activity.

Two Ni-added poly(polyoxometalate)s built of Keggin-type {Ni6PW9} and Anderson-type NiW6O24 units via WO4/Sb2O bridges and Ni-O-W linkages, Na4H8[Ni(enMe)2][(Sb2O)2(NiW6O24)-{Ni12O2(OH)4(enMe)4(H2O)3(WO4)2(B-α-PW9O34)2}2]·39H2O (1) and H9[Ni(en)2(H2O)][Ni0.5(en)2(H2O)][Ni-(enMe)2(H2O)][(Sb2O)2(NiW6O24){Ni12O2(OH)4(en)2(enMe)2(H2O)3(WO4)2}-{Ni12O2(OH)4(en)4(H2O)3(WO4)2}(B-α-PW9O34)4]·45H2O (2), have been hydrothermally synthesized and characterized, in which the {Ni12(WO4)2(PW9)2} subunit was obtained by the synergistic directing effect of 2 lacunary PW9O34 (PW9) fragments and further linked by a central Anderson-type (Sb2O)2(NiW6O24) bridge. Both compounds represent the first example of Ni-added polyoxometalates (POMs) simultaneously based on Keggin-type and Anderson-type POM components. Photocatalytic studies revealed that 2 can work as an efficient heterogeneous catalyst towards a light-driven H2 evolution reaction, achieving a hydrogen evolution rate of as high as 19 214 μmol g-1 h-1 (TON = 1500), which is superior to most of the reported POM-based heterogeneous catalysts.