Electrocatalytic Activity For HER Research Articles

Type-II CuFe2O4/Graphitic Carbon Nitride Heterojunctions for High-Efficiency Photocatalytic and Electrocatalytic Hydrogen Generation.

Solar water splitting has emerged as an urgent imperative as hydrogen emerges as an increasingly important form of energy storage. g-C3N4 is an ideal candidate for photocatalytic water splitting as a result of the excellent alignment of its band edges with water redox potentials. To mitigate electron-hole recombination that has limited the performance of g-C3N4, we have developed a semiconductor heterostructure of g-C3N4 with CuFe2O4 nanoparticles (NPs) as a highly efficient photocatalyst. Visible-light-driven photocatalytic properties of CuFe2O4/g-C3N4 heterostructures with different CuFe2O4 loadings have been examined with two sacrificial agents. An up to 2.5-fold enhancement in catalytic efficiency is observed for CuFe2O4/g-C3N4 heterostructures over g-C3N4 nanosheets alone with the apparent quantum yield of H2 production approaching 25%. The improved photocatalytic activity of the heterostructures suggests that introducing CuFe2O4 NPs provides more active sites and reduces electron-hole recombination. The g-C3N4/CuFe2O4 heterostructures furthermore show enhanced electrocatalytic HER activity as compared to the individual components as a result of which by making heterostructures g-C3N4 with CuFe2O4 increased the active catalytic surface for the electrocatalytic water splitting reaction. The enhanced faradaic efficiency of the prepared heterostructures makes it a potential candidate for efficient hydrogen generation. Nevertheless, the designed heterostructure materials exhibited significant photo- and electrocatalytic activity toward the HER, which demonstrates a method for methodically enhancing catalytic performance by creating heterostructures with the best energetic offsets.

Vanadium-Based Trimetallic Metal-Organic-Framework Family as Extremely High-Performing and Ultrastable Electrocatalysts for Water Splitting.

This is the first time that the pore-space-partition (PSP) strategy is being successfully applied in the electrochemical field for water splitting, realizing the highly efficient construction of a series of ultrastable pristine MOF electrocatalysts. On integrating the vanadium-based trimetallic building cluster (M2V), the target M2V-MOFs exhibit excellent electrocatalytic activity for HER, OER, and water splitting. In particular, ultralow overpotentials of 314 and 198 mV for Fe2V-MOF as OER and HER electrocatalysts, respectively, can drive a current density of 10 mA cm-2. The fabricated Fe2V-MOF||Pt/C two-electrode configuration for the overall water splitting yields a current density of 10 mA cm-2 at only 1.6 V vs RHE, which is superior to that of the commercial IrO2||Pt/C couple. Notably, high structural and chemical stabilities still can be observed in alkaline condition. This work opens up an exciting pathway to design efficient and stable electrocatalysts based on pristine MOF by integrating the PSP strategy and multimetallic centers.

Role of water structure in alkaline water electrolysis

SummaryHerein, with the help of experimental and first-principles density functional theory (DFT)-based studies, we have shown that structural changes in the water coordination in electrolytes having high alkalinity can be a possible reason for the reduced catalytic activity of platinum (Pt) in high pH. Studies with polycrystalline Pt electrodes indicate that electrocatalytic HER activity reduces in terms of high overpotential required, high Tafel slope, and high charge transfer resistances in concentrated aqueous alkaline electrolytes (say 6 M KOH) in comparison to that in low alkaline electrolytes (say 0.1 M KOH), irrespective of the counter cations (Na+, K+, or Rb+) present. The changes in the water structure of bulk electrolytes as well as that in electrode-electrolyte interface are studied. The results are compared with DFT-based analysis, and the study can pave new directions in studying the HER process in terms of the water structure near the electrode-electrolyte interface.

Preparation and characterization of antimony nanoparticles for hydrogen evolution activities

Modern research focuses exclusively on the search for relatively inexpensive, highly efficient electrocatalytic materials for the electrocatalytic hydrogen production water splitting reactions. Antimony is a chemical element having four allotropes with three oxidation states. Antimony is a semi-metal with elemental antimony. Recently, elemental antimony (Sb) with an extensive light absorption was recognized as good electrocatalytic for hydrogen evolution reactions. This study focuses on preparation and characterization of antimony nanoparticles for hydrogen evolution activities as explored. We report the structural, optical, vibrational, electrochemical properties of the pristine antimony nanoparticles for efficient catalytic material for electrochemical water splitting applications. The prepared antimony nanoparticles revealed the rhombohedral crystal structure formation with D3d5 (R 3¯ m) space group situated on symmetry C3v sites. In Raman studies, the peak appeared at 110.67 cm−1 corresponds to in-plane longitudinal vibration (Eg) and at 147 cm−1 for out of plane vibration (A1g) for pure antimony. The synergic effect of NMP and ultrasonication yields highly homogeneous antimony nanoparticles as evidenced from morphological analysis. From electrochemical impedance analysis, the solution resistance value of Sb-NMP is 1.67 Ω, which was small in comparison to the pure Sb (1.96 Ω) and Sb-Ball (1.93 Ω) and exhibited the good conductive nature of Sb-NMP nanomaterials. From electrochemical HER analysis, we found that the Sb-NMP showed the low 246 mV@10 mA/cm2 overpotential with low 186 mV/dec Tafel slope value. Furthermore, the chronoamperometry study exposed that the electrocatalyst Sb-NMP delivered an exceptional HER performance with high stability of 80% retention for continuous three hours measurements. Therefore, this study may perhaps facilitate the growth of antimony nanoparticles which can be used as an HER catalysts for improving the electrocatalytic HER activity.

Exceptional co-catalysts free SrTiO3 perovskite coupled CdSe nanohybrid catalyst by green pulsed laser ablation for electrochemical hydrogen evolution reaction

In this study, a facile and green PLAL technique was used to synthesize nanohybrids consisting of SrTiO3/CdSe, as efficient cathode material for electrocatalytic HER in a basic medium. Although pure SrTiO3 perovskite has poor electrocatalytic performance, but the addition of CdSe has significantly enhanced its electrocatalytic HER activity. Synergistic interactions between SrTiO3 and CdSe are critical to enhance the nanohybrid's electrocatalytic HER performance. An optimized concentration of SrTiO3/CdSe demonstrated a significant current density of -10 mA/cm2 at an overpotential of 224.2 mV, which is much better than the same current density achieved with bare SrTiO3 and CdSe alone at overpotentials of 375.9 mV and 399.4 mV, respectively. SrTiO3/CdSe nanohybrid follows intermediate hydrogen adsorption, which is explained by the Volmer-Heyrovsky step mechanism. The incorporation of CdSe into SrTiO3 improved the nanohybrid's electrocatalytic HER performance by increasing the electrochemical surface area and number of active sites, hence facilitating the electron transfer at the semiconductor-electrolyte interface.

Different loading of Ni2P nanoparticles supported on Co-N-doped ordered macro-/mesoporous carbon for hydrogen evolution reaction

Herein, different loading of Ni2P nanoparticles anchored on 3D Co-N-doped ordered macro-/mesoporous carbon (Ni2P/CoN-OMMC) were synthesized. The optimized Ni2P/CoN-OMMC-40 ​wt% catalyst with 40 ​wt% Ni2P loading exhibits the best electrocatalytic HER activity under strong acidic conditions, showing an extremely low overpotential of 69 ​mV at 10 ​mA ​cm−2 and a small Tafel slope of 38 ​mV dec−1. The highly distributed active Ni2P nanoparticles and the unique macro-mesoporous CoN-OMMC support that is beneficial for promoting the active site exposure and mass/electron transport may contribute synergistically to the remarkable HER catalytic performance.

Electrochemical surface reconstructed Ptx(x=2,3)Si/PtSi/p-Si photocathodes for achieving high efficiency in photoelectrochemical H2 generation

ESR converted the PtSi to Ptx(x=2,3)Si with high electrocatalytic activity for HER. Combined with the high Schottky barrier caused by DS, the Ptx(x=2,3)Si/PtSi/p-Si exhibited excellent PEC H2 generation performance, achieving ABPE as high as 5.8%.

Electronic regulation of a core–shell NiSe2 catalyst by Co doping to accelerate hydrogen evolution

A Co-doping core–shell shaped NiSe2 based catalyst (NixCo1−xSe2@NC) exhibits promising electrocatalytic activity for HER with a low overpotential of −143 mV at −10 mA cm−2, a small Tafel slope of 37.5 mV dec−1.

Self-assembly patterns of non-metalloid silver thiolates: structural, HR-ESI-MS and stability studies.

Screening of AgNO3/AgStBu solutions in DMF, DMSO and NMP resulted in the isolation of three novel nanosized silver/thiolate complexes with a torus-like {Ag20(StBu)10} core. The structures of [NO3@Ag20(StBu)10(NO3)9(DMF)6] (1) and [NO3@Ag20(tBuS)10(NO3)8(NMP)8][NO3@Ag19(tBuS)10(NO3)8(NMP)6]2(NO3) (2) were studied by single crystal X-ray diffraction (SCXRD). The self-assembly process leading to 1 can be switched to a different outcome using Br-, resulting in [Br@Ag16(StBu)8(NO3)5(DMF)3](NO3)2 (3), which is the one of the few genuine host-guest complexes in the silver/thiolate systems. Solutions of the individual complexes in CH3CN were studied by HR-ESI-MS techniques, which revealed a dynamic behavior for each complex, driven by a redistribution of the {AgNO3} units. This dynamics results in the appearance of both cationic and anionic species, based on unchanged silver-thiolate cores. Daylight causes degradation of 3 with the formation of a composite material based on defective orthorhombic Ag2S with a porous morphology, as observed using the SEM technique. The electrocatalytic HER activity of such a material was studied.

A concise discussion on MoS2basal plane activation toward the ennoblement of electrocatalytic HER output

The activation of the chemically inert basal plane of 2H-MoS2 can be achieved by inducing pores and generating vacancies by several other techniques toward enhanced electrocatalytic HER activity.

Electrochemical stability and degradation of commercial Rh/C catalyst in acidic media

Electrochemical stability of a commercial Rh/C catalyst has been studied in an acidic electrolyte by accelerated degradation protocols (ADP) which involved 5000 rapid voltammetric scans (1 V/s) in two potential regions: ADP1 was performed between 0.4 VRHE and 1.4 VRHE, while ADP2 was performed between 0.05 VRHE and 1.4 VRHE. Degradation of Rh/C was monitored by the changes in Rh electrochemical surface area (ECSA) and electrocatalytic activity for hydrogen evolution (HER) and oxygen reduction (ORR). Rh/C catalyst was particularly stable during ADP1 showing only a minor loss of ECSA, while its electrocatalytic activity for HER and ORR was practically unaffected, which was further corroborated with identical location SEM (IL-SEM) imaging. In the case of ADP2, severe degradation of Rh/C occurred followed by substantial decay in its electrocatalytic activity. Coupling of the electrochemical flow cell (EFC) with ICP-MS revealed much higher Rh dissolution in ADP2 than in ADP1. IL-SEM in combination with ex-situ TEM imaging showed that degradation of the Rh/C sample is not homogeneous during ADP2, as dissolution prevails on certain locations, while dissolution followed by re-deposition occurs on others. According to the results obtained in this work, Rh/C catalysts are exceptionally sensitive to the sudden potential jumps between particularly low and high values.

Assembly of Copolymer and Metal-Organic Framework HKUST-1 to Form Cu2-xS/CNFs Intertwining Network for Efficient Electrocatalytic Hydrogen Evolution.

The construction of complex intertwined networks that provide fast transport pathways for ions/electrons is very important for electrochemical systems such as water splitting, but a challenge. Herein, a three dimensional (3-D) intertwined network of Cu2−xS/CNFs (x = 0 or 0.04) has been synthesized through the morphology-preserved thermal transformation of the intertwined PEG-b-P4VP/ HKUST-1 hybrid networks. The strong interaction between PEG chains and Cu2+ is the key to the successful assembly of PEG-b-P4VP nanofibers and HKUST-1, which inhibits the HKUST-1 to form individual crystalline particles. The obtained Cu2−xS/CNFs composites possess several merits, such as highly exposed active sites, high-speed electronic transmission pathways, open pore structure, etc. Therefore, the 3-D intertwined hierarchical network of Cu2−xS/CNFs displays an excellent electrocatalytic activity for HER, with a low overpotential (η) of 276 mV to reach current densities of 10 mA cm−2, and a smaller Tafel slope of 59 mV dec−1 in alkaline solution.

CuFe electrocatalyst for hydrogen evolution reaction in alkaline electrolysis

The development of high performance, stable catalyst with non-precious metals for electrochemical hydrogen evolution reaction for alkaline electrolysis is in demand. Here-in, we report the synthesis of CuFe layered double hydroxide (LDH) electrocatalyst on nickel foam via facile hydrothermal method. In alkaline electrolysis with 1 M NaOH electrolyte, CuFe LDH as cathode requires an overpotential of 159 mV to generate current density of 10 mA cm−2. Which is ca. 51 mV and 7 mV lower than NiFe LDH and NiRu LDH. CuFe LDH exhibits significant electrocatalytic activity for HER. The higher catalytic activity of CuFe LDH compared to NiFe LDH may be achieved with higher proton adsorption by Cu compared to Ni. Also, the efficient charge transfer with interconnected LDH layers, favourable three dimensional structure facilitating easy electrolyte transfer to the active sites and hydrogen gas diffusion. This work may help in developing low cost and efficient hydroxide catalyst.

Construction of a self-supporting Ni2P–WO3 heterostructure for highly efficient hydrogen evolution under both caustic and acidic conditions

An amorphous Ni2P–WO3/CC based HER catalyst is constructed through a facile and scalable method. The catalyst exhibits excellent electrocatalytic HER activity and two-electrode overall water splitting performance in alkaline solutions.

Ru single atoms and nanoclusters on highly porous N-doped carbon as a hydrogen evolution catalyst in alkaline solutions with ultrahigh mass activity and turnover frequency

Ruthenium single atoms and ruthenium nanoclusters dispersed in hierarchically porous N-doped carbon significantly increase the Ru atom efficiency towards excellent electrocatalytic HER activity in alkaline media.

Boosting Electrocatalytic Hydrogen Evolution of Nickel foam Supported Nickel Hydroxide by Ruthenium Doping

AbstractHydrogen evolution reaction (HER) in acid electrolytes has advantages for electrolysis of water due to large supply of hydrogen ions. Herein, we report the synthesis of ruthenium doped nickel hydroxide on commercial nickel foam (Ru−Ni(OH)2/NF) by using simple hydrothermal method. Due to integrated assembly and porous structure, as prepared Ru−Ni(OH)2/NF is explored as an electrocatalyst for HER in 0.5 M H2SO4 solution at room temperature. The Ru−Ni(OH)2/NF showed excellent electrocatalytic HER activity with Tafel slope of 94 mV/dec. The overpotential of Ru−Ni(OH)2/NF required to deliver 10 mAcm−2 current density was calculated to be 27 mV, which is smaller than that of commercial Pt/C/NF catalyst (33 mV). Furthermore, the Ru−Ni(OH)2/NF has shown decent stability and notable durability. The enhanced HER activity of Ru−Ni(OH)2/NF is attributed to Ru doping Ni(OH)2/NF and effective contacts between the Ru−Ni(OH)2 and NF substrate. Finally, these results may provide guidance to the design of Pt‐free catalysts for effective energy related electrocatalytic applications.

Synthesis of Co9S8 nanoparticle embedded, N, S Co-doped mesoporous carbon with salts as templates for electrocatalytic hydrogen evolution

A series of Co9S8 nanoparticles (NPs) entrapped, N, S co-doped carbons were fabricated by using salts as the templates, which involved grounding, carbonation, and acid washing. Various inorganic salts, such as NaCl, KCl, MgCl2, and AlCl3, could be used as the porogens. The porosities of the products could be tuned by the ratios of precursors, annealing temperatures, and kinds of salts. When KCl was adopted, the sample of K-GTCo0.6-900 showed a high BET surface area (773 m2 g−1). Furthermore, the electrocatalytic results exhibited that the high surface area could enhance electrocatalytic activity for HER under alkaline condition. To deliver 10 mA cm−2, K-GTCo0.6-900 possessed low overpotential of 196 mV, as well as good stability.

Waste PET plastic derived ZnO@NMC nanocomposite via MOF-5 construction for hydrogen and oxygen evolution reactions

Waste PET plastic is the main solid waste to deteriorate the environment. Herein, we have utilized waste PET plastic to synthesize nitrogen doped mesoporous carbon functionalized zinc oxide (ZnO@NMC) nanocomposite through MOF-5 construction by low temperature solvothermal method for the first time. As per current energy needs, sustainable hydrogen production through water splitting is the modern appealing solution across the globe. The existence of carbon and nitrogen in ZnO@NMC nanocomposite were confirmed by several analytical techniques i.e. XRD, FTIR, CHN, and XPS. High specific surface area of (939 m2/g) and meso-porosity (pore radius ~25 Å) may offer large number of active sites and easy charge relocation for hydrogen and oxygen evolution reactions via electro-catalysis. The prepared ZnO@NMC nanocomposite exhibits enhanced electro-catalytic activity for HER and OER in 0.5 M KOH solution. Tafel slope and over-potential (ƞ10) of ZnO@NMC nanocomposite were found to be ~108 mV/dec and 0.39 mV, correspondingly, for HER in 0.5 M KOH. ZnO@NMC nanocomposite also shows efficient OER electro-activity with Tafel slope and over-potential (ƞ10) of ~318 mV/dec and ~0.57 V respectively. ZnO@NMC nanocomposite shows better electro-catalytic performance compared to the reported pure ZnO nanostructures. Moreover, the constancy test was also checked through chrono-amperometry (CA) at fixed potential.

Modulating ternary Mo–Ni–P by electronic reconfiguration and morphology engineering for boosting all-pH electrocatalytic overall water splitting

Developing low-cost and highly active heterogeneous catalysts toward electrocatalytic water splitting is highly desirable and the challenges still remain. Herein, we construct a novel bimetallic phosphide catalyst (Mo–Ni–P) by the means of electronic reconfiguration and morphology engineering technology for both hydrogen evolution reaction and oxygen evolution reaction (HER and OER). Benefiting from the attractive nano-architectures of honeycomb spheres and the synergistic effect of Ni and Mo element with exposed abundant active sites, the optimized Mo–Ni–P exhibits satisfactory electrocatalytic activity for HER and OER. Meanwhile, theoretical density functional calculations reveal that the ternary electrocatalyst extremely facilitates the electrical activity and reduces the hydrogen adsorption energy. When explored as both the cathode and anode, the cell voltage was required by a low value of 1.589 V to reach the current density of 10 mA/cm2 in alkaline solution, suggesting the remarkable bifunctional electrocatalytic performance for overall water splitting. This work not only provides insights into the structure-property relationships, but also developed an effective approach to design and prepare high-efficiency water-splitting electrocatalysts.

Synthesis and characterization of Ni2P and MoS2 on MWCNT as an innovative catalytic material for hydrogen generation

In this paper, we report the synthesis and characterization of a material composed of MoS2 nanosheets and Ni2P nanoparticles supported on MWCNT, employing two different routes. In the first one, MoS2 nanosheets were supported on MWCNT followed by a thermal decomposition reaction to grow Ni2P nanoparticles to obtain Ni2P/MoS2/MWCNT. For the second one a mixture of MoS2/MWCNT, synthesized by a solvothermal method, with Ni2P/MWCNT, synthesized by a thermal decomposition reaction method, was prepared to obtain (Ni2P,MoS2)/MWCNT. SEM and TEM images of Ni2P/MoS2/MWCNT and (Ni2P, MoS2)/MWCNT, show their morphology. For Ni2P/MoS2/MWCNT, Ni2P grown on the surface of MoS2/MWCNT, and for (Ni2P, MoS2)/MWCNT, the mixture was clearly identified. X-ray diffraction pattern confirms the formation of Ni2P on the MoS2/MWCNT in Ni2P/MoS2/MWCNT and (Ni2P, MoS2)/MWCNT composed of Ni2P, MoS2, each one supported on MWCNT. It was observed that compared to Ni2P/MWCNT, MoS2/MWCNT, and Ni2P/MoS2/MWCNT, the mixture of (Ni2P, MoS2)/MWCNT exhibits the best electrocatalytic activity for HER with a low onset overpotential of 50.42 mV (vs. RHE) and a small Tafel slope of 47 mV/dec. Also, the compound showed good stability for 50 h. The impedance spectroscopic study also confirmed that charge transfer resistance of (Ni2P, MoS2)/MWCNT is lower (19.7 Ω) than Ni2P/MoS2/MWCNT (86.5 Ω).