Synergistic effect to unlock the activity and stability for oxygen evolution reaction in spinel LiMn2O4 via d-block metal substitution

An effective strategy using d -block metal hybridization was proposed to induce electronic interaction and promote the synergistic effect , aiming to enhance the OER performance of cost-effective spinel LiMn 2 O 4 . Indeed, we deployed a series of LiNi x Mn 2- x O 4 catalysts substituted with Ni, yielding the increase of Mn valence states from Mn 3.5+ to Mn 4+ . The LiNi 0.5 Mn 1.5 O 4 catalyst achieved an excellent OER performance in alkaline media , with an overpotential reduction more than 320 mV at 10 mA cm −2 compared to the unsubstituted LiMn 2 O 4 , as well as the electrochemical stability. It was shown to be superior to the most reported Mn-based oxides OER electrocatalysts . Theoretical calculations demonstrated that Ni doped holes in the Mn site, leading to an increase in Mn 4+ , and that the shared covalent network of Ni 3 d -O 2 p -Mn 3 d optimized an easier desorption of intermediates. These results pave a new example for modulating the chemisorption strength , thus enabling activating the activity and stability of OER process for cost-effective electrocatalysts based on spinel Mn oxides.