Mesoporous Mn-doped FeP: facile synthesis and enhanced electrocatalytic activity for hydrogen evolution in a wide pH range

Min Wang, Yongxiao Tuo, Xiaoke Li, Qingfeng Hua, Luhua Jiang *

Nanomaterial and Electrocatalysis Laboratory, College of Materials Science & Engineering, Qingdao University of Science & Technology, 53 Zhengzhou Road, Qingdao 266042, PR China.

E-mail: luhuajiang@qust.edu.cn (L. Jiang)

Abstract

Water electrolysis is a clean and efficient approach to produce hydrogen on a large scale. Among the reported non-precious metal catalysts for the cathodic hydrogen evolution reaction (HER), iron phosphide is one of the most promising candidate; however, the catalytic activity of FeP is far behind Pt. Herein, we report a highly efficient and durable mesoporous Mn-doped FeP (Mn-FeP) catalyst for the HER via a facile and controllable synthesis route. Electrochemical tests demonstrate that Mn doping leads to enhanced HER performance of mesoporous FeP in a wide pH range. With the Mn-FeP catalyst, the overpotential of the HER to reach a current density of 10 mA cm^-2 is 69, 157 and 173 mV in the H₂SO₄, PBS and KOH electrolyte, respectively, which is 21, 40 and 54 mV less than that of its counterpart mesoporous FeP. Combining the experimental results and the DFT calculation, it is concluded that the enhanced HER activity of Mn-FeP is ascribed to both the accessible active sites benefiting from the mesoporous structure and the appropriate thermo-neutral hydrogen adsorption free energy. Heteroatom doping is an effective strategy to modulate the electron structure of TMPs and is expected to provide a new avenue to promote the HER activity of TMPs.

Keywords: Hydrogen evolution; Water electrolysis; Mn-doped FeP; Mesoporous material; DFT

DOI:10.1021/acssuschemeng.9b01952