Design targeted high entropy sulfides catalysts for OER by theoretical predictions

Abstract

Currently, using Density Functional Theory (DFT) to drive the synthesis of targeted oxygen evolution reaction (OER) catalysts, has attracted strong attention. Herein, sulfides were selected as the models. First, the density of states (DOS), active sites and the Gibbs free energy of intermediates (ΔG) of different models were calculated respectively. DFT results indicated that d-band centers of models with sulfur vacancies, self-reconstruction, or high entropy structures possessing lower ΔG_max, being closer to the Fermi level, exhibiting higher DOS at the Fermi level. To verify DFT results, thiourea was used as a precursor to prepare (CrMnCoNiMo)_0.2S_x for the first time. Indeed, (CrMnCoNiMo)_0.2S_x exhibited excellent OER activity (η₁₀₀ = 266 mV, Tafel slope = 57.4 mV dec⁻¹) and strong catalytic stability. The sulfur vacancies were confirmed by EPR experiments. TEM, XPS and ICP-AES all confirmed the leaching of Cr and Mo elements after OER. XPS, TEM and In situ Raman confirmed the self-reconstruction of (CrMnCoNiMo)_0.2S_x during the OER. The above experimental results perfectly confirmed the initial DFT calculation.