Interfacing nickel nitride and nickel boosts both electrocatalytic hydrogen evolution and oxidation reactions

Abstract

Electrocatalysts of the hydrogen evolution and oxidation reactions (HER and HOR) are of critical importance for the realization of future hydrogen economy. In order to make electrocatalysts economically competitive for large-scale applications, increasing attention has been devoted to developing noble metal-free HER and HOR electrocatalysts especially for alkaline electrolytes due to the promise of emerging hydroxide exchange membrane fuel cells. Herein, we report that interface engineering of Ni3N and Ni results in a unique Ni3N/Ni electrocatalyst which exhibits exceptional HER/HOR activities in aqueous electrolytes. A systematic electrochemical study was carried out to investigate the superior hydrogen electrochemistry catalyzed by Ni3N/Ni, including nearly zero overpotential of catalytic onset, robust long-term durability, unity Faradaic efficiency, and excellent CO tolerance. Density functional theory computations were performed to aid the understanding of the electrochemical results and suggested that the real active sites are located at the interface between Ni3N and Ni.

Ni3N as an Active Hydrogen Oxidation Reaction Catalyst in Alkaline Medium

“…But this specific activity is slightly lower than that of most active hybrid Ni catalysts . Recently a Ni/Ni 3 N/nickel foam catalyst was reported to have very high geometric activity in HOR . The active site was proposed as the interfacial sites of Ni and Ni 3 N, instead of Ni 3 N itself.…”

Mesoporous Ternary Nitrides of Earth-Abundant Metals as Oxygen Evolution Electrocatalyst

“…In the N 1s region (Fig. 3c), the spectrum can be deconvoluted into a combination of two components at 397.5 and 399.2 eV for nitrided samples [44]. Page 6 of 13 https://doi.org/10.1007/s40820-020-0412-8 © The authors…”

Identification of Key Reversible Intermediates in Self‐Reconstructed Nickel‐Based Hybrid Electrocatalysts for Oxygen Evolution

“…X‐ray photoelectron spectroscopy (XPS) was performed to investigate the surface elemental chemical states of NiNPS. As shown in the high‐resolution Ni 2p spectra (Figure f), a shift of 0.3 eV towards higher binding energy (BE) for low‐valence Ni is observed after phosphorization (853.5 eV), compared to that of NiN (853.2 eV, labeled as Ni δ+ , δ is close to 0), indicating electron transfer from Ni to P. A positive shift of 0.34 eV of Ni−N bonding from 398.31 to 398.65 eV further demonstrates the stronger electron affinity of P (Figure g). The S 2p spectra show two split peaks at 162.38 and 163.61 eV accompanying with a satellite peak from oxide (Supporting Information, Figure S4), suggesting the formation of Ni−S bonding .…”