Electrocatalytic Activity For Hydrogen Evolution Reaction Research Articles

Ratio design of bimetallic Pd‐Rh nanoparticles on MoS2 nanosheets: Excellent electrocatalysts for hydrogen evolution reaction

The decrease in noble metal content presents an efficient approach to attain commercial, effective, and durable electrocatalysts for the hydrogen evolution reaction (HER) at a low fabrication cost. Nonetheless, achieving a proper balance between bimetallic loading ratios and HER performance remains challenging. In this study, a simple and environmentally friendly sonochemical method is employed to successfully synthesize bimetallic palladium–rhodium nanoparticles (Pd‐Rh) with varying ratios, confined within molybdenum disulfide (MoS2) nanosheets. Bimetallic Pd‐Rh/MoS2 composite with different ratios of Pd:Rh is synthesized by adjusting the feed ratio of Pd and Rh precursors (1:4, 1:1, and 4:1). The HER electrocatalytic activity of the bimetallic Pd1‐Rh1/MoS2 composite exhibits the lowest overpotential and a superior Tafel slope, closely rivaling the electrocatalytic activity of the commercial 20 wt% Pt/C. Furthermore, the bimetallic Pd1‐Rh1/MoS2 composite exhibits remarkable stability and durability, with almost negligible performance decay after 2000 cycles. These outstanding HER electrocatalytic properties of the bimetallic composite result from a higher number of active sites, a significantly larger electrochemically active surface area, reduced charge‐transfer resistance, and a larger double‐layer capacitance. These factors collectively facilitate faster adsorption and desorption of hydron on the surface of electrocatalyst.

One-step hydrothermal synthesis of nanowire-like W/Mo-Ni3S2/NF electrocatalysts for highly efficient hydrogen evolution reactions

The design of nanostructures and the adjustment of components are very important to improve the performance of hydrogen evolution electrocatalysts. In this paper, Ni, W and Mo trimetallic catalysts are studied from the aspects of morphology, structure and electronic transfer, and a better combination of hydrogen reaction efficiency is obtained. The W/Mo co-doped nickel sulfide electrocatalyst was synthesized on Ni foam by one-step hydrothermal method. As anticipated, the individual incorporation of either tungsten (W) or molybdenum (Mo) into the electrocatalyst did not yield satisfactory enhancements in hydrogen evolution reaction (HER) performance. However, when both W and Mo were co-doped onto the electrocatalyst, a significant improvement in catalyst material performance was observed. Hence, the coexistence of W and Mo is the key to improve HER electrocatalytic activity. In 1 M KOH solution, the W/Mo-Ni3S2/NF electrocatalyst exhibited exceptional HER activity with an overpotential of only 136 mV at a current density of 10 mA·cm−2 and demonstrated excellent cycle stability exceeding 20 hours. In this paper, the strategy of bimental co-doping composite is adopted to adjust the structure of nickel sulfide, which provides reference value for the design of reasonable and efficient HER electrocatalyst.

Investigation of Palladium-doped 2D g-C3N5 materials for enhanced electrocatalytic activity towards hydrogen evolution reaction

Hydrogen is widely recognized as an extremely environmentally friendly energy source due to its unique characteristics, notably its high energy density and complete absence of carbon emissions. The electrocatalytic technique is the most efficient for hydrogen production among various techniques. Designing an electrocatalyst that is highly electrochemically efficient, catalytically active, stable, cost-effective, and environmentally durable, especially in harsh conditions (highly acidic and basic), is still challenging. Herein, the new set of compositions of Pd-doped g-C3N5 was successfully synthesized by a simple carbonization method using a mixture of 3-amino-1,2,4-triazole (3AT) and PdCl2. Among these materials, nanosheets synthesized g-C3N5/Pd-1% with the optimized ratio demonstrate the most impressive electrocatalytic performance for the hydrogen evolution reaction (HER). This material exhibits a very low onset overpotential of approximately -10 mV vs. RHE, the smallest Tafel slope value of 47.6 mV dec-1, and achieves a current density of 10 mV/cm−2 at an overpotential of 69 mV vs. RHE. The catalytic materials also offer very good stability and durability for electrocatalytic HER activity. The upgraded catalytic activity towards HER of g-C3N5/Pd-1% results from the improved and easy charge transfer and optimized synergism between Pd and g-C3N5. Hence, the synthesized g-C3N5/Pd-1% materials could potentially serve as a substitute for Pt-based electrocatalysts in practical hydrogen production for the hydrogen evolution reaction (HER).

Phenoxide coordination to Fe(III) tetraphenylporphyrin: Exploring antibacterial and electrocatalytic HER activity

Herein, we report synthesis, solid and solution state structure as well as properties of three five coordinate (unsubstituted, 4-NO2 substituted and 2,4,6 trinitro substituted) phenoxide axially ligated to Fe(III)-tetraphenyl porphyrins. Spectroscopic characterization revealed high-spin (S = 5/2) nature of the phenoxide bound Fe(III) porphyrins (Fe1 and Fe2). However, the 2,4,6 trinitro substituted phenoxide axially ligated Fe(III) porphyrin (Fe3) demonstrate spin admixed nature (S = 5/2, 3/2) with predominate high spin contribution. (Phenolato)(porphinato)iron(III) complexes merit attention owing to structural analogy with the catalase enzyme. In this study we investigated their antibacterial as well as electrocatalytic hydrogen evolution reaction (HER) activity. Fe1 demonstrate potent antibacterial activity against gram-negative E. coli (MTCC 443) and gram-positive Staphylococcus aureus (MTCC 3160) human pathogenic bacteria. It also produce catalytic current for electrocatalytic HER activities upon gradual addition of PTSA (para-tolunesulphonic acid) as proton source. Compounds Fe2 and Fe3 also produce enhanced catalytic wave which originate possibly from reduction of proton coupled with reduction of –NO2 group.

Molten salts etching route driven construction of C@Ni nanoparticles loaded carbon nanosheet as high-performance electrocatalyst for hydrogen evolution reaction

Developing earth-abundant, low-cost, high-efficiency electrocatalysts for hydrogen evolution reaction (HER) by structure design is still a grand challenge. Herein, we fabricated Ni nanoparticles encapsulated by carbon loaded in two-dimensional carbon nanosheets (2D Ni@C@SU) using a molten salt (NaCl)-assisted pyrolysis method. Because of the large specific surface area (262.35 m²/g) and high electrical conductivity, the prepared 2D Ni@C@SU-0.75 electrocatalyst exhibits excellent HER electrocatalytic activity with the overpotential of −105 mV at −10 mA cm−2 and −367 mV at −200 mA cm−2, which is close to the commercial benchmark Pt/C (η200= −339 mV). Besides, the catalyst displays incredible durability in the electrocatalytic HER. This research indicates that the green solid-state synthetic strategy provides a new window for designing new Ni-based composite catalysts for electrocatalytic HER.

Aqueous pH influence on the electrocatalytic hydrogen evolution reaction with carbon nanotube-supported diiron dithiolato compound

Biomimetic chemistry on structure, function and external environment of [FeFe]-hydrogenases for hydrogen evolution reaction (HER) has shown a promising way to develop non-precious metal electrocatalysts for H2 production in the current Pt-dominated HER system. Herein, three new diiron dithiolato compounds [{(μ-SCH2)2N(C6H4CH2CO2R)}Fe2(CO)6] (R = H (1), C6H4CHO-p (2), and C6H4Me-m (3)) were first prepared and identified as a library of [FeFe]-hydrogenase models in this work. Subsequently, the as-prepared diiron molecule 2 can be covalently attached onto carbon nanotubes (CNTs), resulting in the obtainment of target CNT-supported [FeFe]-hydrogenase model labeling as covalent hybrid 2Fe2S-f-CNT. Notably, the electrocatalytic HER performance and stability of the resulted hybrid 2Fe2S-f-CNT immobilized respectively on a gassy carbon (GC) electrode are systematically studied and compared in 0.1 M KOH (pH = 13), 0.1 M phosphate buffer (pH = 7), and 0.05 M H2SO4 (pH = 1) aqueous solutions by various spectroscopic and electrochemical techniques. The result has shown that the higher electrocatalytic HER activity is observed in alkaline solution (pH = 13) relative to neutral and acidic solutions (pH = 7, 1), being attributed to the different electrochemical HER processes of diiron cluster in wide pH aqueous media as revealed by post operando analysis.

Construction of Z-type In2O3@InP heterostructure with enhanced photo-assisted electrocatalytic water splitting for hydrogen production

We report an in-situ construction strategy of Z-type In2O3@InP hydrogen evolution reaction (HER) electrocatalyst with well-defined core-shell structure on nickel foam (In2O3@InP/NF) via sequential hydrothermal, annealing, and phosphating steps. The phosphating time dramatically affects the morphology, crystal phase, elemental composition, and optical properties of In2O3@InP. The resulting electrode obtained with 2 h of phosphating time has smaller overpotentials and Tafel slope, larger TOF and ECSA, and lower charge transfer resistance compared to In2O3/NF. The better activity reveals the promoted roles of InP that can provide more active sites, facilitate charge transfer, and accelerate the adsorption of H* species. The photo-assisted electrocatalytic activity for HER is significantly enhanced attributed to the strong light absorption capacity of InP, superior energy level configuration of In2O3 and InP, and excellent transient light response of In2O3@InP. Furthermore, the electrode has favorable stability and durability, and the morphology and surface chemical state have no essential changes after the photo-assisted HER stability test.

Comparative study on various morphologies of WS2 for electrochemical hydrogen evolution reaction

Nowadays, the advancement of cost-effective and efficient electrocatalysts holds significant importance in facilitating the progress of high-performance electrochemical hydrogen evolution reaction (HER). Tungsten disulfides (WS2) are well recognized as highly promising electrocatalysts for HER due to their exceptional catalytic performance, outstanding stability, and comparatively affordable price. In this study, we used ammonium metatungstate hydrate and thioacetamide as precursors to fabricate WS2 nanoflowers (NFs) by hydrothermal method, whereas WS2-flakes were prepared from ammonium tetrathiotungstate through the thermolysis technique. These structures were evaluated for HER electrocatalytic activity in acidic media. The results revealed that WS2-NFs exhibit higher catalytic activity than WS2-flakes, with an overpotential of 325 mV to obtain a current density of 10 mA cm−2 and a Tafel slope of 92.3 mV dec−1. This performance was attributed to the larger electrochemically active surface area of WS2-NFs compared to WS2-flakes materials. The results of this study could bring the basis for further studies on the synthesis of WS2-based catalytic materials for HER. ® 2023 Journal of Science and Technology - NTTU

Dissolution-Induced Surface Reconstruction of Ni0.95 Pt0.05 Si/p-Si Photocathode for Efficient Photoelectrochemical H2 Production.

Metal silicide/Si photoelectrodes have demonstrated significant potential for application in photoelectrochemical (PEC) water splitting to produce H2 . To achieve an efficient and economical hydrogen evolution reaction (HER), a paramount consideration lies in attaining exceptional catalytic activity on the metal silicide surface with minimal use of noble metals. Here, this study presents the design and construction of a novel Ni0.95 Pt0.05 Si/p-Si photocathode. Dopant segregation is used to achieve a Schottky barrier height as high as 1.0eV and a high photovoltage of 420mV. To achieve superior electrocatalytic activity for HER, a dissolution-induced surface reconstruction (SR) strategy is proposed to in situ convert surface Ni0.95 Pt0.05 Si to highly active Pt2 Si. The resulting SR Ni0.95 Pt0.05 Si/p-Si photocathode exhibits excellent HER performance with an onset potential of 0.45V (vs RHE) and a high maximum photocurrent density of 40.5mAcm-2 and a remarkable applied bias photon-to-current efficiency (ABPE) of 5.3% under simulated AM 1.5 (100mWcm-2 ) illumination. The anti-corrosion silicide layer effectively protects Si, ensuring excellent stability of the SR Ni0.95 Pt0.05 Si/p-Si photoelectrode. This study highlights the potential for achieving efficient PEC HER using bimetallic silicide/Si photocathodes with reduced Pt consumption, offering an auspicious perspective for the cost-effective conversion of solar energy to chemical energy.

Facile fabrication of MoS2 and MoSe2 layered structures on Mo foil for the efficient photocatalytic dye degradation and electrocatalytic hydrogen evolution reaction

The rapidly growing necessity for sustainable materials in fields such as energy, environmental science, and medicine, two dimensional-based photo- and electro-catalysts has obtained mounting consideration. A simple methodology was employed to fabricate MoSe2 and MoS2 layered structures on flexible Mo foil as heterogeneous catalysts for the electrocatalytic hydrogen evolution reaction (HER) and the photocatalytic decolorization of chromic red (CR) and methylene blue (MB) dyes. The structural characteristics confirm the formation of the multi-layer thick MoSe2 and MoS2 nanofilms. The toxic MB and CR dyes were rapidly and effectively decolorized in polluted water by the photocatalysts within 30 min of UV-light irradiation. The fabricated layered structures exhibited favorable HER electrocatalytic activities along with low overpotentials, small Tafel slopes, and excellent 24-h stability performances. The strong catalytic behavior of these structures fabricated on Mo foil in relation to the HER reaction and the dye decolorization process make them suitable candidates for the catalyst industry.

Ir nanoclusters on ZIF-8-derived nitrogen-doped carbon frameworks to give a highly efficient hydrogen evolution reaction

The precise change of the electronic structure of active metals using low-active supports is an effective way of developing high-performance electrocatalysts. The electronic interaction of the metal and support provides a flexible way of optimizing the catalytic performance. We have fabricated an efficient hydrogen evolution reaction (HER) electrocatalyst, in which Ir nanoclusters are uniformly loaded on a nitrogen-doped carbon framework (Ir@NC). The synthesis process entails immersing an annealed zeolitic imidazolate framework-8 (ZIF-8), prepared at 900 °C as a carbon source, into an IrCl3 solution, followed by a calcination-reduction treatment at 400 °C under a H2/Ar atmosphere. The three-dimensional porous structure of the nitrogen-doped carbon framework exposes more active metal sites, and the combined effect of the Ir clusters and the N-doped carbon support efficiently changes the electronic structure of Ir, optimizing the HER process. In acidic media, Ir@NC has a remarkable HER electrocatalytic activity, with an overpotential of only 23 mV at 10 mA cm−2, an ultra-low Tafel slope (25.8 mV dec−1) and good stability for over 24 h at 10 mA cm−2. The high activity of the electrocatalyst with a simple and scalable synthesis method makes it a highly promising candidate for the industrial production of hydrogen by splitting acidic water.

Comparative study on various morphologies of WS2 for electrochemical hydrogen evolution reaction

Nowadays, the advancement of cost-effective and efficient electrocatalysts holds significant importance in facilitating the progress of high-performance electrochemical hydrogen evolution reaction (HER). Tungsten disulfides (WS2) are well recognized as highly promising electrocatalysts for HER due to their exceptional catalytic performance, outstanding stability, and comparatively affordable price. In this study, we used ammonium metatungstate hydrate and thioacetamide as precursors to fabricate WS2 nanoflowers (NFs) by hydrothermal method, whereas WS2-flakes were prepared from ammonium tetrathiotungstate through the thermolysis technique. These structures were evaluated for HER electrocatalytic activity in acidic media. The results revealed that WS2-NFs exhibit higher catalytic activity than WS2-flakes, with an overpotential of 325 mV to obtain a current density of 10 mA cm−2 and a Tafel slope of 92.3 mV dec−1. This performance was attributed to the larger electrochemically active surface area of WS2-NFs compared to WS2-flakes materials. The results of this study could bring the basis for further studies on the synthesis of WS2-based catalytic materials for HER.
 ® 2023 Journal of Science and Technology - NTTU

Benzene-fused porphyrin(2.1.2.1) array: synthesis, structure, and electrocatalytic hydrogen evolution.

The development of efficient molecular catalysts for the electrocatalytic hydrogen evolution reaction (HER) is very necessary and important for fuel cells. In this work, we report a new benzene-fused porphyrin(2.1.2.1) array, BPD, with a unique S-shaped molecular conformation. The electrochemistry of BPD displays multielectron donating and accepting properties owing to the two porphyrin(2.1.2.1) blocks and degenerate molecular orbitals. The electrocatalytic HER activity of BPD is remarkably higher-that is, BPD exhibited lower overpotential, faster HER kinetics, faster charge transfer kinetics, and extended catalytic stability-than that of the porphyrin(2.1.2.1) copper complex monomer.

Bi-cation incorporated Ni3N nanosheets boost water dissociation kinetics for enhanced alkaline hydrogen evolution activity.

Nickel nitride (Ni3N) is a promising electrocatalyst for the hydrogen evolution reaction (HER) owing to its excellent metallic features and has been demonstrated to exhibit considerable activity for water oxidation. However, its undesirable characteristics as an HER electrocatalyst due to its poor unfavourable d-band energy level significantly limit its water dissociation kinetics. Herein, the HER electrocatalytic activity of Ni3N was prominently enhanced via the simultaneous incorporation of bi-cations (vanadium (V) and iron (Fe), denoted as V-Fe-Ni3N). The optimized V-Fe-Ni3N displays impressive performance with an overpotential of 69 mV at 10 mA cm-2 and good stability in 1.0 M KOH, which is remarkably better than pristine Ni3N, V-doped Ni3N, and Fe-doped Ni3N and considerably closer to a commercial Pt/C catalyst. Based on density functional theory (DFT) studies, V and Fe atoms not only serve as active sites for promoting water dissociation kinetics but also tune the electronic structure of Ni3N to achieve optimized hydrogen adsorption capabilities. This work presents an inclusive understanding of the rational designing of high-performance transition metal nitride-based electrocatalysts for hydrogen production. Its electrocatalytic performance can be significantly enhanced by doping transition metal cations.

Pt Single-Atom collaborate with Pt Atom-Clusters by an In-Situ confined strategy for accelerating electrocatalytic hydrogen evolution

Heterogeneous catalysts with atomic dispersion play an important role in electrocatalysis. In addition to the single-atom, modifying the intrinsic catalytic capacity of single-atom catalysts through cooperative atom-clusters is an effective way to increase active sites and improve mass activity. Herein, a composite electrocatalytic material (PtM@CN) with partial Pt single-atoms and partial Pt atom-clusters was obtained by pyrolysis of the thermostable UiO-66-PtTCPP precursor. Remarkably, beneficial to the synergistic effect of Pt single-atom and Pt atom-clusters as well as the strong metal-support interaction, the PtM@CN catalyst showed excellent hydrogen evolution reaction (HER) activity and stability in both acidic and alkaline electrolytes. Moreover, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations shows that the existence of Pt single-atom and Pt atom-clusters could rationally adjust electronic structure of supported metals and impact adsorption energy of reaction intermediates, which play an essential role in enhancing the electrocatalytic activity of HER.

Phase-engineered heterostructures of Mo2C by plasma-assisted selenization and sulfurization processes toward excellent hydrogen evolution reaction

Due to the outstanding semiconducting and metallic properties, 2D materials such as Transition Metal dichalcogenides (TMDs) and Transition Metal Carbides (TMCs) appear to be promising candidate for Nano-scale electronics devices. Among them, 2D - Mo2C (Molybdenum carbide) has attracted attention as a new member of the MXene group, owing to its potential applications for superconductors, electronics devices, and catalysts for Hydrogen evolution Reactions (HER). Structural modification toward the creation of novel heterostructures with phase engineering opens new pathways for different applications. Herein, we prepared a large area Mo2C film by chemical vapor deposition method. The upper region of Mo2C layers can be oxidized to create Mo2C/MoOx heterostructures. Furthermore, those oxide layers were further transformed into MoSe2 and MoS2 by plasma-assisted selenization and sulfurization processes at different temperatures with a fixed plasma power of 150 W. The heterostructures demonstrated outstanding electrocatalytic activity for HER due to an existed metallic phase and active sites present after plasma-assisted selenization and sulfurization processes at the low temperature. The performance of the HER decreases at high temperatures owing to their semiconducting phase. The pristine Mo2C showed a Tafel slope of 72 mV dec−1 and an overpotential of 276 mV at 10 mA/cm2, while the Mo2C/MoSe2 heterostructure synthesized at 350 °C350 °exhibited an improved Tafel slope of 66 mV dec−1 and overpotential of 257 mV at 10 mA/ cm2. Additionally, the Mo2C/MoS2 heterostructure prepared at 350 °C also demonstrated a 263 mV improvement in overpotential at 10 mA/cm2. All the heterostructures showed excellent stability over a period of 10 h except Mo2C/MoOx. This work opens new strategies to fabricate high-quality MXene and TMDs heterostructures with metal-semiconductor interface.

In Situ Construction of a Co2P/CoP Heterojunction Embedded on N-Doped Carbon as an Efficient Electrocatalyst for a Hydrogen Evolution Reaction.

Noble metal-free electrocatalysts have received widespread attention in a hydrogen evolution reaction (HER) due to the importance of renewable energy development. Herein, a Co2P/CoP heterojunction embedded on an N-doped carbon (Co2P/CoP/NC) electrocatalyst was prepared via an in situ pyrolysis method. The as-prepared electrocatalyst exhibited efficient electrocatalytic activity for HER in an acidic solution. The Co2P/CoP/NC catalyst displayed an overpotential of 184 mV at 10 mA cm-2 and a low Tafel slope of 82 mV dec-1, which could be attributed to the tight Co2P/CoP heterojunction and the synergetic effect of Co2P/CoP and N-doped carbon. In addition, the electrochemical active surface area of Co2P/CoP/NC was 75.2 m2 g-1, which indicated that more active regions can be applied for the HER process. This report may pave a new way for the design of efficient and low-cost N-doped-carbon-supported 3d transition metal phosphide electrocatalysts.

Layered Nanocomposites of Polymer-Functionalized Reduced Graphene Oxide and Borocarbonitride with MoS2 and MoSe2 and Their Hydrogen Evolution Reaction Activity

Two dimensional heterostructure have been widely investigated for various applications in electrochemistry such as water splitting and battery storage. These heterostructures are mainly formed due to vander waals interaction, covalent cross-linking and electrostatic interactions. Herein, we have prepared nanocomposite of positively charged poly (diallyldimethylammonium chloride) (PDDA, shown as P)-functionalized reduced graphene oxide (RGO) and borocarbonitride (BC6N, shown as BCN for simplicity) sheets with layers of negatively charged MoS2 and MoSe2 by electrostatic interaction in solution phase. The nanocomposites exhibit superior photocatalytic hydrogen evolution reaction (HER) activity compared to the individual components, and the value increases with the MoS2/MoSe2 content. The highest photocatalytic HER activity obtained is 11230 μmol h–1 g–1 in the nanocomposite P.RGO-MoS2, with a P.RGO-MoS2 ratio of 1:5. The P.RGO-MoSe2 (1:5) and P.BCN-MoS2 (1:5) nanocomposites exhibit somewhat lower activities of 9540 and 8593 μmol h–1 g–1, respectively. Prompted by literature reports that carbon-rich BCNs are efficient HER electrocatalysts, we have examined the electrocatalytic HER activity of P.BCN-MoS2 (1:1, 1:5, and 1:7) nanocomposites. The electrocatalytic HER activity of P.BCN-MoS2 (1:5) is found to be extraordinary, with an onset potential of −50 mV (vs RHE), comparable to that of platinum.

Titanium Nanotubes as an Effective Electrocatalyst Support for Hydrogen Evolution Reaction

Developing proper support for hydrogen evolution reaction (HER) electrocatalysts is important for enhancing the HER efficiency and reducing the cost of green hydrogen production. TiO2-based-catalyst support has attracted considerable attention due to its commercial availability, high stability, low cost, and its unique electronic and ionic properties [1]. TiO2 is commonly utilized in various applications involving, photocatalysis, solar cells, and photoelectrochemical water splitting [2]. The ease of the synthesis of TiO2 with different morphologies and crystal structures makes it promising support to replace carbon in electrochemical applications [3]. Recently, anatase TiO2 nanoparticles decorated with PtOx clusters showed benchmark activity toward hydrogen evolution from the acidic medium with an overpotential of –125 mV at –10 mA cm–2 [4]. Furthermore, Pt clusters supported on porous TiO2 nanoparticles achieved higher stability compared with that of the benchmark Pt/C catalyst due to the facile electron transfer from TiO2 to PtOx [4]. Despite the TiO2-supported Pt nanoclusters have been recently investigated, the characteristic of HER electrocatalysts loaded on highly ordered TiO2 nanotube arrays (TNTs) is still unexplored. TNTs are expected to be an optimal support architecture owing to their large internal surface area and excellent electron mobility [5, 6]. Moreover, they can be readily synthesized and have robust mechanical stability. Therefore, in our work, highly ordered TNTs on Ti substrate have been synthesized and investigated as a support for different types of HER electrocatalysts (i.e. PtOx [7], MoS2 [8], and CoOP [9]). The PtOx clusters supported on TNTs (Ti/TNTs/PtOx) showed excellent performance for HER. An overpotential of –30 mV was sufficient to deliver –10 mA cm–2 from the acidic medium. The electrocatalytic mass activity of Ti/TNTs/PtOx (i.e. 204 mA mgPt –1) is enhanced by 12 and 1.7-fold compared to those of Pt/C and titanium nanoparticles (TNPs) supported PtOx electrocatalysts, respectively. The superior activity of the Ti/TNTs/PtOx is mainly due to its large electrochemically active surface area and the excellent electron mobility in the TNTs support. The immobilizing of MoS2 on TNTs resulted in enhanced electrocatalytic HER activity. An overpotential of –200 mVRHE was ample to deliver –10 mA cm–2 from 0.5 M H2SO4 aqueous solution. A synergy between the in-situ immobilized MoS2 and TNTs is proposed to explain the enhanced HER performance. In an alkaline medium, the Ti/TNTs/CoOP electrode fabricated by incorporating CoOP spheres into the TNTs exhibited only –130 mV overpotential to deliver –10 mA cm–2. This value is superior to that of CoOP deposited on bare Ti foil (–165 mV), FTO (–185 mV), and glassy carbon (–214 mV). In general, our study revealed that the TNTs support improves the electrochemical surface area and accessibility of active sites while reducing the charge transfer resistance at the electrode/electrolyte interface. Acknowledgments T.A.K. thanks the Deanship of Research Oversight and Coordination at KFUPM for the conference attendance support.

Electrocatalytic Hydrogen Evolution of Transition Metal (Fe, Co and Cu)–Corrole Complexes Bearing an Imidazole Group

The study of the hydrogen evolution reaction (HER) by non-noble transition metals is of great significance for the production of hydrogen energy. In this work, a new 5,15-bis-(pentafluorophenyl)-10-[4-(1H-imidazole) phenyl]-corrole and its metal complexes (metal = Co, Cu, Fe) were synthesized and used for electrocatalyzed HER in DMF organic solvent and aqueous media. The prepared cobalt corrole showed the best catalytic performance in both media. Its turnover frequency (TOF) and catalytic efficiency (C.E) could reach 265 s−1 and 1.04 when TsOH was used as the proton source in a DMF solvent. In aqueous media, its TOF could also reach 405 h−1. The catalytic HER may go through an EECEC or ECEC (E: electron transfer, C: chemical step) pathway for these catalysts, depending on the acidity and concentration of the proton source. The present work successfully demonstrates that imidazole at a meso-phenyl group may improve the electrocatalytic HER activity of transition metal corroles.