Electronic regulation and mechanism research of NiCo hydroxides for the electrocatalytic glucose oxidation reaction.

Element synergy is a brilliant strategy for improving electrocatalytic performance. Herein, the element synergy of Ni-M LDHs (M = Al, Co, Cr, Cu, Fe, Li, Mg, Mn, and Zn) is investigated in the electrocatalytic glucose oxidation reaction (GOR). Among these catalysts, the Ni0.25Co0.75 LDH shows the lowest potential of 1.201 V for achieving a current density of 10 mA cm-2. Furthermore, LSV plots indicate that formyl groups and polyhydric alcohols in glucose are more easily catalyzed by the Ni0.25Co0.75 LDH than methanol. NMR spectroscopy proves that part of the glucose can be catalyzed by the Ni0.25Co0.75 LDH to form formate. In situ Raman spectra show that the Ni0.25Co0.75 LDH first transforms into NixCo1-x oxyhydroxides and then into NixCo1-x oxides with increasing potential. When the voltage drops, part of NixCo1-x oxide phase fails to return to its initial oxidation, which leads to a certain degree of lattice distortion. DFT calculations reveal that the synergistic effects of Ni and Co play a major role in optimizing both thermodynamics and kinetics.