Design of high-performance ion-doped CoP systems for hydrogen evolution: From multi-level screening calculations to experiment

Rational design of high-performance electrocatalysts for hydrogen evolution reaction (HER) is vital for future renewable energy systems. The incorporation of foreign metal ions into catalysts can be an effective approach to optimize its performance. However, there is a lack of systematic theoretical studies to reveal the quantitative relationships at the electronic level. Here, we develop a multi-level screening methodology to search for highly stable and active dopants for CoP catalysts. The density functional theory (DFT) calculations and symbolic regression (SR) were performed to investigate the relationship between the adsorption free energy (ΔGH*) and 10 electronic parameters. The mathematic formulas derived from SR indicate that the difference of work function (ΔΦ) between doped metal and the acceptor plays the most important role in regulating ΔGH*, followed by the d-band center (d-BC) of doped system. The descriptor of HER can be expressed as ΔGH∗=1.59×0.188ΔΦ+dBC+0.120-0.166 with a high determination coefficient (R2 = 0.807). Consistent with the theoretical prediction, experimental results show that the Al-CoP delivers superior electrocatalytic HER activity with a low overpotential of 75 mV to drive a current density of 10 mA cm−2, while the overpotentials for undoped CoP, Mo-CoP, and V-CoP are 206, 134, and 83 mV, respectively. The current work proves that the ΔΦ is the most significant regulatory parameter of ΔGH* for ion-doped electrocatalysts. This finding can drive the discovery of high-performance ion-doped electrocatalysts, which is crucial for electrocatalytic water splitting.