Partial carbonization and etching of ZIF-9 to construct SO42−-decorated C@NiCoFe LDH ultrathin nanosheets for efficient oxygen evolution reaction

Abstract

Rationally designed catalysts with rich catalytic sites and great conductivity are effective for the oxygen evolution reaction (OER). Herein, we use a multiple compound strategy, which contains the partial pyrolysis and etching of ZIF-9, to prepare the SO₄²⁻ and Fe co-doped NiCo layered double hydroxide (LDH) coupled with the CoNC and synergistically regulate the OER activity. The existence of CoNC improves the conductivity, while Fe³⁺ and SO₄²⁻ dual regulation ensures C@NiCoFe–SO₄ with rich active sites and optimized adsorption energy for OER intermediates. Theoretical calculation further proves that the introduced Fe ion and CoNC support change the rate determining step in the OER and promote charge transfer, thus accelerating the catalytic process. As expected, C@NiCoFe–SO₄ delivers a low overpotential (234 mV @ 10 mA cm⁻²) for the OER in 0.1 M KOH. Besides, the electrolyzer of C@NiCoFe–SO₄(+)‖Pt/C(−) requires a low cell voltage of 1.45 V at 10 mA cm⁻² for water splitting in 1.0 M KOH. Multiple strategy combination provides an interesting option for rational design of multi-metal OER catalysts.