Synergy of Cu doping and SO42− adsorption in the self-optimized SO42−@Cu doped Co(OH)2 reconstructed from CuCo2S4 towards enhanced oxygen evolution reaction

Catalysts in-situ reconstructed from transition metal sulfides for oxygen evolution reaction (OER) have been regarded as potential alternatives for the noble metal catalysts . Intriguingly, it was found that the self-optimized SO 4 2− @Cu doped Co(OH) 2 catalyst was reconstructed from bimetallic sulfide of CuCo 2 S 4 . During the OER process, the copper was partially leached and meantime doped into the in-situ generated Co(OH) 2 with SO 4 2− adsorption, while only oxides were discovered in counterparts of mono-metal sulfides. As a result, the SO 4 2− @Cu doped Co(OH) 2 catalyst exhibited superior OER performances, with low overpotentials of 211/272 mV to achieve the current densities of 10/100 mA cm −2 , exceeding the counterparts reconstructed from mono-metal sulfides. Experimental and theoretical results suggested that the in situ generated Cu doped Co(OH) 2 possessed thin and loosely layered structure with expanded lattice spacing (lattice spacing expanded from 0.28 nm to 0.46 nm) due to the SO 4 2− adsorption, making the intermediates more accessible to the active centers. In addition, the catalyst surface changed from hydrophobicity to super hydrophilicity , which greatly accelerated the mass transfer. This work indicated that the in-situ reconstruction process was greatly influenced by the interactions between metal sites and sulfide species, directly influencing the OER performances of the reconstructed catalysts.