Electrode reconstruction strategy for oxygen evolution reaction: maintaining Fe-CoOOH phase with intermediate-spin state during electrolysis

Abstract

Computational calculations and experimental studies reveal that the CoOOH phase and the intermediate-spin (IS) state are the key factors for realizing efficient Co-based electrocatalysts for the oxygen evolution reaction (OER). However, according to thermodynamics, general cobalt oxide converts to the CoO2 phase under OER condition, retarding the OER kinetics. Herein, we demonstrate a simple and scalable strategy to fabricate electrodes with maintaining Fe-CoOOH phase and an IS state under the OER. The changes of phase and spin states were uncovered by combining in-situ/operando X-ray based absorption spectroscopy and Raman spectroscopy. Electrochemical reconstruction of chalcogenide treated Co foam affords a highly enlarged active surface that conferred excellent catalytic activity and stability in a large-scale water electrolyzer. Our findings are meaningful in that the calculated results were experimentally verified through the operando analyses. It also proposes a new strategy for electrode fabrication and confirms the importance of real active phases and spin states under a particular reaction condition.

Oxygen Evolution Reaction in Energy Conversion and Storage: Design Strategies Under and Beyond the Energy Scaling Relationship

“…However, the distributed and intermittent nature of such renewable energy sources presents a formidable challenge toward their effective utilization [1][2][3]. Exploring high-performance energy conversion and storage (ECS) devices, such as small molecule (water, carbon dioxide and nitrogen) electrolyzers, rechargeable metal-air batteries, and regenerative fuel cells, that can harvest, convert and store the renewable energy in chemicals and then reconvert at the point of need, is therefore of essential importance but remains a great scientific challenge [4][5][6][7][8][9][10][11][12]. The oxygen evolution reaction (OER) is the essential module in these ECS devices since it supplies electrons required for electrochemical conversion cycles between renewable electricity and chemical fuels [13][14][15][16].…”

Recent Progress in Transition-Metal Sulfide Catalyst Regulation for Improved Oxygen Evolution Reaction

“…The CoOOH phase and the intermediate-spin (IS) state were proposed to be the key factors for realizing efficient Co-based electrocatalysts for OER, as revealed by the computational calculations and experimental studies. A simple and scalable strategy to fabricate a Co-based catalyst with a stable Fe-CoOOH phase and an IS state under the OER surface was proposed by treating the raw Co foam (CF) with iron and sulfur via a construction strategy under alkaline OER conditions . This electrode showed a remarkable OER activity of 192 mV to offer 10 mA cm –2 , and good durability for 150 h at 100 mA cm –2 for a large-scale water electrolysis cell, because of the highly porous and rough surface with enlarged active surface area.…”

Active Sites Regulation for High-Performance Oxygen Evolution Reaction Electrocatalysts

“…Meanwhile, Co 3 O 4 did not change significantly in the process of high potential and OER test by comparing the absorption spectra of Co 3 O 4 under different voltages, which means that Co 3 O 4 can maintain a very stable structure under the condition of OER reaction; thus, considerable efforts have been devoted to exploring efficient Co 3 O 4 electrocatalysts. Co 3 O 4 belongs to the spinel family, in which Co +2 and Co +3 play different roles in OER process ( García-Mota et al, 2012 ; Bergmann et al, 2015 ; Lee et al, 2022 ) Wang et al ( Bo et al, 2005 ) studied the role of Co +2 and CO +3 ions in the OER process by replacing Co +2 with Zn and Co +3 with Al. The results show that the OER activity of CoAl 2 O 4 (in the presence of Co +2) is similar to that of Co 3 O 4 (in the presence of Co+2), but superior to that of ZnCo 2 O 4 (in the presence of Co +3), which confirms that the bivalent Co+2 plays a dominant role in OER activity.…”