Multifunctional Active-Center-Transferable Platinum/Lithium Cobalt Oxide Heterostructured Electrocatalysts towards Superior Water Splitting

Designing cost-effective and efficient electrocatalysts plays a pivotal role in advancing the development of electrochemical water splitting for hydrogen generation. Herein, multifunctional active-center-transferable heterostructured electrocatalysts, platinum/lithium cobalt oxide (Pt/LiCoO₂) composites with Pt nanoparticles (Pt NPs) anchored on LiCoO₂ nanosheets, are designed towards highly efficient water splitting. In this electrocatalyst system, the active center can be alternatively switched between Pt species and LiCoO₂ for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Specifically, Pt species are the active centers and LiCoO₂ acts as the co-catalyst for HER, whereas the active center transfers to LiCoO₂ and Pt turns into the co-catalyst for OER. The unique architecture of Pt/LiCoO₂ heterostructure provides abundant interfaces with favorable electronic structure and coordination environment towards optimal adsorption behavior of reaction intermediates. The 30 % Pt/LiCoO₂ heterostructured electrocatalyst delivers low overpotentials of 61 and 285 mV to achieve 10 mA cm⁻² for HER and OER in alkaline medium, respectively.     

Multifunctional Active‐Center‐Transferable Platinum/Lithium Cobalt Oxide Heterostructured Electrocatalysts towards Superior Water Splitting

Designing cost‐effective and efficient electrocatalysts plays a pivotal role in advancing the development of electrochemical water splitting for hydrogen generation. Herein, multifunctional active‐center‐transferable heterostructured electrocatalysts, platinum/lithium cobalt oxide (Pt/LiCoO₂) composites with Pt nanoparticles (Pt NPs) anchored on LiCoO₂ nanosheets, are designed towards highly efficient water splitting. In this electrocatalyst system, the active center can be alternatively switched between Pt species and LiCoO₂ for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Specifically, Pt species are the active centers and LiCoO₂ acts as the co‐catalyst for HER, whereas the active center transfers to LiCoO₂ and Pt turns into the co‐catalyst for OER. The unique architecture of Pt/LiCoO₂ heterostructure provides abundant interfaces with favorable electronic structure and coordination environment towards optimal adsorption behavior of reaction intermediates. The 30 % Pt/LiCoO₂ heterostructured electrocatalyst delivers low overpotentials of 61 and 285 mV to achieve 10 mA cm^?2 for HER and OER in alkaline medium, respectively.     

Enhancing the Hydrogen Evolution Reaction Activity of Platinum Electrodes in Alkaline Media Using Nickel–Iron Clusters

Herein, we demonstrate an easy way to improve the hydrogen evolution reaction (HER) activity of Pt electrodes in alkaline media by introducing Ni–Fe clusters. As a result, the overpotential needed to achieve a current density of 10 mA cm^?2 in H₂‐saturated 0.1 m KOH is reduced for the model single‐crystal electrodes down to about 70 mV. To our knowledge, these modified electrodes outperform any other reported electrocatalysts tested under similar conditions. Moreover, the influence of 1) Ni to Fe ratio, 2) cluster coverage, and 3) the nature of the alkali‐metal cations present in the electrolyte on the HER activity has been investigated. The observed catalytic performance likely originates from both the improved water dissociation at the Ni–Fe clusters and the subsequent optimal hydrogen adsorption and recombination at Pt atoms present at the Ni–Fe/Pt boundary.     

Harmonious Heterointerfaces Formed on 2D-Pt Nanodendrites by Facet-Respective Stepwise Metal Deposition for Enhanced Hydrogen Evolution Reaction

The performance of nanocrystal (NC) catalysts could be maximized by introducing rationally designed heterointerfaces formed by the facet- and spatio-specific modification with other materials of desired size and thickness. However, such heterointerfaces are limited in scope and synthetically challenging. Herein, we applied a wet chemistry method to tunably deposit Pd and Ni on the available surfaces of porous 2D−Pt nanodendrites (NDs). Using 2D silica nanoreactors to house the 2D-PtND, an 0.5-nm-thick epitaxial Pd or Ni layer ( e - Pd or e -Ni ) was exclusively formed on the flat {110} surface of 2D−Pt, while a non-epitaxial Pd or Ni layer ( n - Pd or n -Ni ) was typically deposited at the {111/100} edge in absence of nanoreactor. Notably, these differently located Pd/Pt and Ni/Pt heterointerfaces experienced distinct electronic effect to influence unequally in electrocatalytic synergy for hydrogen evolution reaction (HER). For instance, an enhanced H₂ generation on the Pt{110} facet with 2D-2D interfaced e -Pd deposition and faster water dissociation on the edge-located n -Ni overpowered their facet-located counterparts in respective HER catalysis. Therefore, a feasible assembling of the valuable heterointerfaces in the optimal 2D n -Ni/e-Pd/Pt catalyst overcame the sluggish alkaline HER kinetics, with a catalytic activity 7.9 times higher than that of commercial Pt/C.     

Galvanostatically Deposited PtNi Thin-Films as Electrocatalysts for the Hydrogen Evolution Reaction

The synthesis of hybrid platinum materials is fundamental to enable alkaline water electrolysis for cost-effective H₂ generation. In this work, we have used a galvanostatic method to co-deposit PtNi films onto polycrystalline gold. The surface concentrations of Ni (Γ_Ni) and Pt (Γ_Pt) were calculated from electrochemical measurements; the Γ_Pt/Γ_Ni ratio and electrocatalytic activity of these materials towards hydrogen evolution reaction (HER) in 1 M KOH show a strong dependence on the current density pulse applied during the electrodeposition. Analysis of the Tafel parameters hints that, on these deposits, HER proceeds through a Volmer-Heyrovsky mechanism. The galvanostatically deposited PtNi layers present a high current output per Pt gram, 3199 A g_Pt⁻¹, which is significantly larger compared to other PtNi-based materials obtained by more extended and more complex synthesis methods.     

The Core/Shell Structure P Doped MoS2@Ni3S2 Nanorods Array for High Current Density Hydrogen Evolution in Alkaline and Acidic Electrolyte

Electrocatalysis is the most promising strategy to generate clean energy H₂, and the development of catalysts with excellent hydrogen evolution reaction (HER) performance at high current density that can resist strong alkaline and acidic electrolyte environment is of great significance for practical industrial application. Therefore, a P doped MoS₂@Ni₃S₂ nanorods array (named P-NiMoS) was successfully synthesized through successive sulfuration and phosphorization. P-NiMoS presents a core/shell structure with a heterojunction between MoS₂ (shell) and Ni₃S₂ (core). Furthermore, the doping of P modulates the electronic structure of the P-NiMoS; the electrons transfer from the t_2g orbital of Ni element to the e_g empty orbital of Mo element through the Ni−S−Mo bond at the Ni₃S₂ and MoS₂ heterojunction, facilitating the hydrogen evolution reaction. As a result, P-NiMoS exhibits excellent HER activity; the overpotential is 290 mV at high current density of 250 mA cm⁻² in alkaline electrolyte, which is close to Pt/C (282 mV@250 mA cm⁻²), and P-NiMoS can stably evolve hydrogen for 48 h.     

Reversible Electrocatalytic Activity of Carbon‐Supported PtxNi1−x in Hydrogen Reactions

Hydrogen oxidation and evolution reactions (HOR and HER) are studied on Pt_xNi_1?x/C materials synthesized by the bromide anion exchange method. Physicochemical characterization shows that this surfactant‐free method enables the preparation of well‐dispersed and effective catalysts for the processes involved in the anode of H₂/O₂ fuel cells (HOR) and the cathode of water electrolyzers (HER). The Pt‐based materials are modified with different Ni contents to decrease the amount of costly precious metal in the electrode materials. These modified Pt‐based materials are found to be electroactive for both reactions without additional overpotential. Kinetic parameters such as the Tafel slope, exchange (j₀) and kinetic current densities, and the rate‐determining steps of the reaction mechanisms are determined for each Pt–Ni catalyst and compared to those obtained at the Pt/C surface in alkaline medium. The high j₀ values that are obtained indicate a probable contribution of the surface structure of the catalysts due to their roughness and the presence of oxygenated Ni species even at low potentials.     

On the electronic structure and hydrogen evolution reaction activity of platinum group metal-based high-entropy-alloy nanoparticles

We report the synthesis of high-entropy-alloy (HEA) nanoparticles (NPs) consisting of five platinum group metals (Ru, Rh, Pd, Ir and Pt) through a facile one-pot polyol process. We investigated the electronic structure of HEA NPs using hard X-ray photoelectron spectroscopy, which is the first direct observation of the electronic structure of HEA NPs. Significantly, the HEA NPs possessed a broad valence band spectrum without any obvious peaks. This implies that the HEA NPs have random atomic configurations leading to a variety of local electronic structures. We examined the hydrogen evolution reaction (HER) and observed a remarkably high HER activity on HEA NPs. At an overpotential of 25 mV, the turnover frequencies of HEA NPs were 9.5 and 7.8 times higher than those of a commercial Pt catalyst in 0.05 M H₂SO₄ and 1.0 M KOH electrolytes, respectively. Moreover, the HEA NPs showed almost no loss during a cycling test and were much more stable than the commercial Pt catalyst. Our findings on HEA NPs may provide a new paradigm for the design of catalysts.

RuRhPdIrPt high-entropy-alloy nanoparticles with a broad and featureless valence band spectrum show high hydrogen evolution reaction activity.     

Support Morphology Effect on Selective Hydrogenation of 3-Nitrostyrene to 3-Vinylaniline over Pt/α-Fe2O3 Catalysts

Selective hydrogenation of substituted nitroaromatic compounds is an extremely important and challenging reaction. Supported metal catalysts attract much attention in this reaction because the properties of metal nanoparticles (NPs) can be modified by the nature of the support. Herein, the support morphology on the catalytic performance of selective hydrogenation of 3-nitrostyrene to 3-vinylaniline was investigated. Pt NPs supported on octadecahedral α-Fe₂O₃ supports with a truncated hexagonal bipyramid shape (Pt/α-Fe₂O₃-O) and rod-shaped α-Fe₂O₃ supports (Pt/α-Fe₂O₃-R) were prepared by glycol reduction method. Detailed characterizations reveal that the electronic structure and dispersion of Pt NPs can be modified by the supports. The Pt/α-Fe₂O₃-O catalyst exhibited superior catalytic performance for hydrogenation of 3-nitrostyrene because of its low coordinated Pt sites and the small Pt NPs size, which is benefit from the high-index exposed surfaces of truncated hexagonal bipyramid-shaped α-Fe₂O₃ support. The structural evolution during the catalytic reaction was investigated in detail by identical location transmission electron microscopy (IL-TEM) method, which found that the high cycling activity of Pt/α-Fe₂O₃-O catalyst during the cycle experiment results from the stability of Pt NPs.     

Boron-Induced Electronic-Structure Reformation of CoP Nanoparticles Drives Enhanced pH-Universal Hydrogen Evolution

Even though transition-metal phosphides (TMPs) have been developed as promising alternatives to Pt catalyst for the hydrogen evolution reaction (HER), further improvement of their performance requires fine regulation of the TMP sites related to their specific electronic structure. Herein, for the first time, boron (B)-modulated electrocatalytic characteristics in CoP anchored on the carbon nanotubes (B-CoP/CNT) with impressive HER activities over a wide pH range are reported. The HER performance surpasses commercial Pt/C in both neutral and alkaline media at large current density (>100 mA cm⁻²). A combined experimental and theoretical study identified that the B dopant could reform the local electronic configuration and atomic arrangement of bonded Co and adjacent P atoms, enhance the electrons’ delocalization capacity of Co atoms for high electrical conductivity, and optimize the free energy of H adsorption and H₂ desorption on the active sites for better HER kinetics.     

Boron‐Induced Electronic‐Structure Reformation of CoP Nanoparticles Drives Enhanced pH‐Universal Hydrogen Evolution

Even though transition‐metal phosphides (TMPs) have been developed as promising alternatives to Pt catalyst for the hydrogen evolution reaction (HER), further improvement of their performance requires fine regulation of the TMP sites related to their specific electronic structure. Herein, for the first time, boron (B)‐modulated electrocatalytic characteristics in CoP anchored on the carbon nanotubes (B‐CoP/CNT) with impressive HER activities over a wide pH range are reported. The HER performance surpasses commercial Pt/C in both neutral and alkaline media at large current density (>100 mA cm^?2). A combined experimental and theoretical study identified that the B dopant could reform the local electronic configuration and atomic arrangement of bonded Co and adjacent P atoms, enhance the electrons’ delocalization capacity of Co atoms for high electrical conductivity, and optimize the free energy of H adsorption and H₂ desorption on the active sites for better HER kinetics.     

pH effect on electrocatalytic reduction of CO2 over Pd and Pt nanoparticles

Adsorbed hydrogen participates in electrocatalytic reduction of CO₂ and competitive hydrogen evolution reaction (HER) simultaneously, and its reaction pathway greatly affects the activity and selectivity of CO₂ reduction. In this work, we investigate pH effect on electrocatalytic reduction of CO₂ over Pd and Pt nanoparticles (NPs) with a similar size in a pH range from 1.5 to 4.2. Pt NPs completely contribute to HER in the pH range. Over Pd NPs, Faradaic efficiency for CO production at − 1.19 V (vs. reversible hydrogen electrode) varies from 3.2% at pH of 1.5 to 93.2% at pH of 4.2, and current density for CO production reaches maximum at pH of 2.2. The significant enhancement of Faradaic efficiency and current density for CO production over Pd NPs at high pH values is attributed to decreased kinetics of hydrogen evolution reaction by increasing hydrogen binding energy and lowered adsorption affinity of CO-like intermediate compared to Pt.     

Ultrafine Molybdenum Carbide Nanoparticles Composited with Carbon as a Highly Active Hydrogen‐Evolution Electrocatalyst

The replacement of platinum with non‐precious‐metal electrocatalysts with high efficiency and superior stability for the hydrogen‐evolution reaction (HER) remains a great challenge. Herein, we report the one‐step synthesis of uniform, ultrafine molybdenum carbide (Mo₂C) nanoparticles (NPs) within a carbon matrix from inexpensive starting materials (dicyanamide and ammonium molybdate). The optimized catalyst consisting of Mo₂C NPs with sizes lower than 3 nm encapsulated by ultrathin graphene shells (ca. 1–3 layers) showed superior HER activity in acidic media, with a very low onset potential of ?6 mV, a small Tafel slope of 41 mV dec^?1, and a large exchange current density of 0.179 mA cm^?2, as well as good stability during operation for 12 h. These excellent properties are similar to those of state‐of‐the‐art 20 % Pt/C and make the catalyst one of the most active acid‐stable electrocatalysts ever reported for HER.     

Phase and Interface Engineering of Platinum–Nickel Nanowires for Efficient Electrochemical Hydrogen Evolution

The design of high‐performance electrocatalysts for the alkaline hydrogen evolution reaction (HER) is highly desirable for the development of alkaline water electrolysis. Phase‐ and interface‐engineered platinum–nickel nanowires (Pt‐Ni NWs) are highly efficient electrocatalysts for alkaline HER. The phase and interface engineering is achieved by simply annealing the pristine Pt‐Ni NWs under a controlled atmosphere. Impressively, the newly generated nanomaterials exhibit superior activity for the alkaline HER, outperforming the pristine Pt‐Ni NWs and commercial Pt/C, and also represent the best alkaline HER catalysts to date. The enhanced HER activities are attributed to the superior phase and interface structures in the engineered Pt‐Ni NWs.     

Heterointerface engineering of Ru/RuS2 on N/S-doped hollow mesoporous carbon for promoting alkaline hydrogen evolution

Alkaline hydrogen evolution reaction (HER) suffers from a sluggish kinetic, which requires the elaborate catalytic interface and micro-nanoscale architecture engineering of the electrocatalysts to accelerate the water dissociation and hydrogen evolution. Herein, the heterointerface engineering was proposed for promoting the alkaline HER by constructing the highly exposed Ru/RuS₂ heterostructures homogeneously distributed on hollow N/S-doped carbon microspheres (Ru/RuS₂@h-NSC). Benefited from the synergistic effect of heterointerfacial Ru/RuS₂, the high accessibility of the active sites on both inner and outer surface of mesoporous shells and the efficient mass transport, Ru/RuS₂@h-NSC affords a remarkable catalytic performance with an overpotential of 26 mV@10 mA/cm² for alkaline HER, outperforming most of the state-of-the-art catalysts. Further applying Ru/RuS₂@h-NSC and its oxidized derivate for the overall alkaline water splitting, the required cell voltage is much lower than that of the commercial Pt/C||RuO₂ pair to achieve the same current density. Our study may allow us to guide the design of micro-nanoreactors with optimal catalytic interfaces for promising electrocatalytic applications.     

General synthesis of Pt and Ni co-doped porous carbon nanofibers to boost HER performance in both acidic and alkaline solutions

It is essential to develop efficient electrocatalysts to generate hydrogen from water electrolysis for hydrogen economy. In this work, platinum(Pt) and nickel(Ni) co-doped porous carbon nanofibers(Pt/NiPCNFs) with low Pt content were prepared via an electrospinning, carbonization and galvanic replacement reaction. Because of the high electrical conductivity, abundant electrochemical active sites and synergistic effect between Pt and Ni nanoparticles, the optimized Pt/Ni-PCNFs catalyst shows an e...     

Structure Evolution and Associated Catalytic Properties of PtSn Bimetallic Nanoparticles

Bimetallic nanoparticles (NPs) often show new catalytic properties that are different from those of the parent metals. Carefully exploring the structures of bimetallic NPs is a prerequisite for understanding the structure‐associated properties. Herein, binary Pt?Sn NPs with tunable composition are prepared in a controllable manner. X‐ray characterizations reveal that their structures evolve from SnO_2?x‐patched PtSn alloys to SnO_2?x‐patched Pt clusters when more tin is incorporated. An obvious composition‐dependent catalytic performance is observed for the hydrogenation of α,β‐unsaturated aldehydes: the selectivity to unsaturated alcohol increases substantially at high tin content, whereas the reaction rate follows a volcano shape. Furthermore, Pt sites are responsible for hydrogen dissociation, whereas oxygen vacancy (O_vac) sites, provided by SnO_2?x, drastically enhance the adsorption of carbonyl group.