In-situ optimizing the valence configuration of vanadium sites in NiV-LDH nanosheet arrays for enhanced hydrogen evolution reaction

Developing the highly active, cost-effective, environmental-friendly, and ultra-stable nonprecious electrocatalysts for hydrogen evolution reaction(HER) is distinctly indispensable for the large-scale practical applications of hydrolytic hydrogen production. Herein, we report the synthesis of well-integrated electrode, NiV layered double hydroxide nanosheet array grown in-situ on porous nickel foam(abbreviated as in-NiV-LDH/NF) via the facile one-step hydrothermal route. Interestingly, the valence configuration of vanadium(V) sites in such NiV-LDH are well dominated by the innovative use of NF as the reducing regulator, achieving the reassembled in-NiV-LDH/NF with a high proportion of trivalent V ions(V3+), and then an enhanced intrinsic electrocatalytic HER activity. The HER testing results show that the in-NiVLDH/NF drives the current densities of 10 and 100 mA cm-2 at extremely low overpotentials of 114 and 245 mV without iR-compensation respectively, even outperforms commercial 20 wt% Pt/C at the large current density of over 80 mA cm-2 in alkaline media, as well as gives robust catalytic durability of at least 100 h in both alkaline and neutral media. More importantly, this work provides a fresh perspective for designing bimetal(oxy) hydroxides electrocatalysts with efficient hydrogen generation.

Polyoxometalate as the assembly material to self-assembled Ni(OH)_(2)nanosheets with electrocatalytic performance

Developing non-noble metal-based electrocatalyst with high catalytic activity is essential for advancing hydrogen energy technologies.This study introduces a hydrothermal method for synthesizing order Ni(OH)_(2)nanosheets,with H_(3)O_(40)PW_(12)(denoted as PW_(12))loaded onto reduced graphene oxide(rGO)coated on nickel foam(referred to as PW_(12)-Ni(OH)_(2)/rGO).This method contrasts with the electrodeposition of Ni(OH)_(2),where PW_(12)is added to the synthetic system to direct the assembly and morphology of the Ni(OH)_(2)through a hydrothermal reaction.In this work,the nickel foam acts dual roles as both the substrate and the source of nickel for the formation of Ni(OH)_(2).The PW_(12)-Ni(OH)_(2)/rGO nanosheets,when successfully prepared and loaded onto the nickel foam(NF),exhibited superior electrocatalytic activity for the hydrogen evolution reaction(HER)in an alkaline electrolyte,achieving a current density of 10 mA·cm^(-2)at an overpotential of 69 mV.Furthermore,we endeavored to expand the application of this material towards the oxygen evolution reaction(OER)by preparing PW_(12)-(Fe/Co)Ni(OH)_(2)/rGO through the addition of metal cations.This nanocomposite displayed outstanding electrocatalytic activity in alkaline electrolytes,with a current density of 10 mA·cm^(-2)at an overpotential of 211 mV,and demonstrated excellent stability over a 50 h period in a 1 M KOH solution.The results presented in this paper offer an effective strategy for the preparation of polyoxometalate-based inorganic materials with diverse functionalities,applicable to both HER and OER.

Nanocomposite: Keggin-type Co_(4)-polyoxometalate@cobaltporphyrin linked graphdiyne for hydrogen evolution in seawater

Polyoxometalate-based nanocomposites with electrocatalytic activity have been applied in hydrogen evolution reactions(HER).Seawater as the main water resource on the earth should be developed as the water electrolysis to prepare high-purity hydrogen.In this paper,we used two synthesis strategies to prepare the nanocomposite Co_(4)-POM@Co-PGDY(Co_(4)-POM:the Kegging-type microcrystals of K_(10)[Co_(4)(PW_(9)O_(3)4)2]and Co-PGDY:cobalt-porphyrin linked graphdiyne)with excellent activity for HER.Co-PGDY as the porous material is applied not only as the protection of microcrystals towards the metal ion in seawater but also as the co-electrocatalyst of Co_(4)-POM.Co_(4)-POM@Co-PGDY exhibits excellent HER performance in seawater electrolytes with low overpotential and high stability at high density.Moreover,we have observed a key H_(3)O+intermediate emergence on the surface of nanocomposite during hydrogen evolution process in seawater by Raman synchrotron radiation-based Fourier transform infrared(SR-FTIR).The results in this paper provide an effective strategy for preparing polyoxometalate-based electrocatalysts with high-performance toward hydrogen evolution reaction.

Dual modulation of morphology and electronic structures of VN@C electrocatalyst by W doping for boosting hydrogen evolution reaction

Developing high-efficiency and robust durability electrocatalyst for hydrogen evolution reaction(HER)in water electrolysis functions as a crucial role for the construction of green hydrogen economy,herein,ultrafine W-doped vanadium nitride nanoparticles anchored on N-doped graphitic carbon framework(WVN@NGC)are synthesized through a one-step simple pyrolysis protocol.Owing to the enlarged catalytically active sites,enhanced electrical conductivity and optimized electronic structure,the resultant VN/WN@NGC delivered the prominent HER performance with overpotentials of 143 mV and 158 mV at10 mA/cm^(2) in acid and alkaline media,respectively,accompanied by the long-term stability for at least50 h.This work highlights a novel strategy for a metal-triggered modulation of nitride-based HER electrocatalyst for sustainable energy conversion device.