Tunable heteroassembly of 2D CoNi LDH and Ti3C2 nanosheets with enhanced electrocatalytic activity for oxygen evolution

Abstract

The sluggish kinetics of the oxygen evolution reaction (OER) is the bottleneck to developing hydrogen energy based on water electrolysis, which can be significantly improved using high performance catalysts. In this context, CoNi layered double hydroxide (LDH)/Ti₃C₂ heterostructures are obtained using electrostatic attraction of the positively charged LDH and negatively charged Ti₃C₂ nanosheets as the catalyst to optimize the OER performance. Such alternate stacking exhibits good catalytic activity with a lower overpotential and a small Tafel slope, outperforming their individual components. The results of density functional theory (DFT) simulation show that the charge transfers from Ti₃C₂ to CoNi LDH not only adjust the electron distribution, but also increase the electron density of the interfacial active sites, thus enhancing the electron transfer efficiency inside the heterostructures. Moreover, the cobalt and nickel ions exhibit a synergistic effect in supplying more electrons to adsorb the adjacent intermediates with active hydrogen and oxygen vacancies, to improve the adsorption capability and to reduce the reaction energy barriers. These findings provide a rewarding avenue towards the design of highly efficient electrocatalysts for OER.