Dual role of sulfur doping in NiCr LDH for water oxidation: promoting surface reconfiguration and lattice oxygen oxidation

Heterogeneous doping is widely applied to improve the oxygen evolution reaction (OER) activity of layered double metal hydroxides (LDH), but it is challenging to study the reconfiguration and reaction mechanism of catalysts. Herein, we prepared sulfur-doped NiCr LDH (Sx-NiCr LDH) pre-catalyst, which exhibits low overpotential of 244.4mV at 100mAcm-2 after reconfiguration. The characterization results reveal that sulfur doping not only optimizes the reconfiguration process of NiCr LDH by modulating Cr leaching, but also reduces the oxidation potential of Ni2+. Density functional theory (DFT) results show that sulfur doping reduces the energy barrier of reconfiguration, enhances the covalency of Ni-O, and upshifts the O 2p band center to promote lattice oxygen oxidation. The reconfigured catalyst requires 1.51 and 1.47V at 10mAcm-2 for overall water splitting at 25 °C and 80 °C, respectively. This work provides a valuable approach for designing highly active LDH catalysts.