Selectively etching manganese from nickel-manganese hydroxides via thiourea corrosion for urea electro-oxidation

Abstract

Ni-based hydroxides have been extensively explored as potential catalysts for urea oxidation reaction. Defect engineering and heteroatoms doping are efficient routes to boost the catalytic activity. In this work, a facile thiourea corrosion strategy is employed to simultaneously generate vacancy defects and dope S in Ni-Mn hydroxides through one-pot ethanol solvothermal approach. Owing to the solubility difference between NiS and MnS in ethanol with thiourea, Mn species can be selectively etched from Ni-Mn hydroxides, and the corrosion degree of Ni-Mn hydroxides can be rationally regulated by variation of thiourea corrosion time. This corrosion strategy will change the morphology and structure of Ni-Mn hydroxides. Significantly, more vacancy defects can be created for Ni-Mn hydroxides after urea corrosion. These changes are beneficial for increasing the number of active sites, and the electronic states of Ni and Mn species can be also regulated. Hence, Ni-Mn hydroxides after thiourea corrosion delivers a much higher current density towards urea oxidation compared with Ni-Mn hydroxides without thiourea corrosion. The enhanced anti-poisoning capacity and accelerated charge transfer efficiency should be responsible for the boosted catalytic performance of Ni-Mn hydroxides with thiourea corrosion. This study gives a new insight to design and activate the Ni-based catalysts towards urea oxidation via creating of more vacancy defects using thiourea corrosion strategy.