Dynamic analysis of equivalent circuit model value of CoP/boron nitride doped carbon for hydrogen evolution reaction

Abstract

Equivalent circuit model (ECM) is one of the most commonly used tools in electrode process analysis such as hydrogen evolution reaction (HER) process in electrochemical impedance spectroscopy experiment. This work attempts to analyze dynamic element values of ECM of cobalt phosphide-boron nitride doped carbon (CoP/BN-C) in HER process during linear sweep voltammetric test with the help of Kalman filter algorithm. Tafel slopes of CoP/BN-C in alkaline solution and in seawater are close (∼106 mV•dec−1) with the overpotential (η) of 154 mV and 545 mV to drive a current density of 10 mA•cm−2, respectively. Polarization resistance (Rpol) of CoP/BN-C calculated from system identification reaches 2.21 kΩ in seawater, which is about twice of the maximum value in alkaline solution. Power analysis can also certificate the difference of catalytic efficiency in different electrolyte. The potential position of the maximum Rpol is close to the position of onset potential. This contribution provides a practical and effective strategy to obtain Rpol from LSV curves and presents a two-dimensional image composed of η and Rpol, which may supplement more information on catalytic activity of HER process in various environments.