Bifunctional CoxP-FeP@C for overall water splitting realized by manipulating the electronic states of Co via phosphorization

Zengyuan Li; Zhi Li; Huiying Yao; Yu Wei; Jinsong Hu

doi:10.1016/j.jcis.2023.09.139

Bifunctional Co_xP-FeP@C for overall water splitting realized by manipulating the electronic states of Co via phosphorization

J Colloid Interface Sci. 2024 Jan;653(Pt A):857-866. doi: 10.1016/j.jcis.2023.09.139. Epub 2023 Sep 23.

Authors

Zengyuan Li¹, Zhi Li², Huiying Yao³, Yu Wei⁴, Jinsong Hu⁵

Affiliations

¹ School of Chemical Engineering, Anhui Provincial Key Laboratory of Specialty Polymers, Anhui University of Science and Technology, Huainan 232001, China.
² School of Chemical Engineering, Anhui Provincial Key Laboratory of Specialty Polymers, Anhui University of Science and Technology, Huainan 232001, China. Electronic address: 2022025@aust.edu.cn.
³ School of Chemical Engineering, Anhui Provincial Key Laboratory of Specialty Polymers, Anhui University of Science and Technology, Huainan 232001, China. Electronic address: hyyao@aust.edu.cn.
⁴ College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, China.
⁵ School of Chemical Engineering, Anhui Provincial Key Laboratory of Specialty Polymers, Anhui University of Science and Technology, Huainan 232001, China; Institute of Energy, Hefei Comprehensive National Science Center, Anhui, Hefei 230031, China. Electronic address: jshu@aust.edu.cn.

PMID: 37769364
DOI: 10.1016/j.jcis.2023.09.139

Abstract

The electronic properties and structural characteristics of transition metal materials have a significant impact on their electrocatalytic performance. Therefore, precisely controlling the electronic states of core metals and fabricating catalysts with advanced structures are conducive to facilitating electrolysis process. Herein, we manipulate the electronic properties of the electroactive sites of catalysts by controlling the degree of phosphorization during the phosphorization process. The Co_xP-FeP@C electrocatalysts, characterized by their sea-urchin morphology, were synthesized by subjecting CoFc-metal organic framework (MOF) precursors to phosphorization for specific time intervals. The optimized Co₂P-FeP@C-5 electrocatalyst showed the optimum performance towards the oxygen evolution reaction (OER) catalytic efficiency with 239 mV overpotential and the hydrogen evolution reaction (HER) activity with 169 mV overpotential to reach 10 mA·cm^-2 in 1.0 M KOH (PH = 13.8). For comparison, the extended duration of phosphorization resulted in the formation of CoP-FeP@C-15 and CoP-FeP@C-30 electrocatalysts, which exhibited compromised electrocatalytic performance due to the transformation of the electroactive core Co₂P to CoP during subsequent phosphorization processes. The improved interfacial properties between Co₂P and FeP play a crucial role in enhancing the efficiency of water decomposition, attributed to the higher density of states (DOS) at the Fermi Level and the increased availability of electroactive sites for the adsorption of intermediates and electrolysis. These findings are substantiated by density functional theory (DFT) calculations. This approach offers a highly effective means of manipulating the electronic properties of the electroactive transition metal core by controlling the degree of phosphorization, with the ultimate goal of achieving efficient water splitting.

Keywords: DFT calculation; Electronic states; Overall water splitting; Phosphorization; Sea-urchin shape.