In Situ Electrochemical Oxyanion Steering of Water Oxidation Electrocatalysts for Optimized Activity and Stability

Abstract

Compared to traditional modulation by metal cations doping, oxyanions offer a higher possibility of mediating the performance of electrocatalysts toward oxygen evolution reaction (OER) due to their special polyanion configurations and large electronegativity. However, the mechanism and rules of oxyanions mediation remain poorly understood. Herein, an in situ electrochemical oxyanion (NO3−, PO43−, SO42−, or SeO42−) steering strategy to study the variation and rules of OER performance for transition‐metal (TM = Ni, Fe, Co) hydroxide electrocatalysts is reported. Electrocatalytic experiments indicate both activity and stability of oxyanion‐modified TM hydroxides follow the order of PO43− > NO3− > SO42− > SeO42−. Electrochemical incorporation of PO43− or NO3− improves activity and stability of TM hydroxides. Conversely, SO42− or SeO42− doping significantly accelerates TM leaching and thus impairs OER performance. Theoretical calculations reveal that electrochemical oxyanion doping simultaneously modulates TM‐O covalency and TM‐3d band centers, correlating with TM stability and OER activity of TM hydroxides. This research constructs an oxyanion‐mediated rule for designing high‐performance electrocatalysts toward energy transformation.

Unveiling the Oxygen Evolution Mechanism with FeNi (Hydr)oxide under Neutral Conditions

“…Phosphate ions act as proton receptors and also induce the distortion of the structure to facilitate the adsorption of water. Recently, Wang et al showed that both the OER activity and stability of oxyanion-modified Ni, Fe, and Co hydroxides follow the order of PO 4 3– > NO 3 – > SO 4 2– > SeO 4 2– …”

Boosting Hydrogen Evolution by Methanol Oxidation Reaction on Ni-Based Electrocatalysts: From Fundamental Electrochemistry to Perspectives

“…124 The electrocatalytic OER influenced by residual or adsorbed anionic species, such as P, S, and Se, was investigated in alkaline media. 126,127 Thus, as shown in Figure 9d, the Wang group grew different oxyanions on commercial nickel foams to study its effects toward MOR by anionic species. And then followed by the in situ electrochemical oxidation in the alkaline, the different coordination environment of these oxyanions (NiOOH-TO x , T= P, S, and Se) of Ni sites were formed (Figure 9e).…”

Trimetallic Oxide Electrocatalyst for Enhanced Redox Activity in Zinc–Air Batteries Evaluated by In Situ Analysis

“…The overlap of Ni K-edge ranges or the absorption edge positions at the different operating voltages indicate the inactive nature of Ni ions during the ORR, as presented in the inset of Figure 3a. [53] Figure S7a,b (Supporting Information) contrasts the pre-edge regions of the Ni and Co K-edges, which pre-edge features in both of these spectra display 1s to 3d electronic transitions. The difference in peak intensity and the absorption edge position often offer structural information that contains the local atomic symmetry and oxidation states of Co. [42,45d,54] The pre-edge feature at 7709 eV in the Co K-edge is similar to CoO, which suggests the octahedral coordination of Co.…”