Engineering d-band center of cobalt active sites via dual coordination with nitrogen-doped carbon nanotube and Ti3C2Tx MXene toward electrocatalytic oxygen reduction for H2O2 production

Abstract

Manipulating the selective adsorption of oxygen-containing species is crucial for tailoring the electrocatalyst to select dual-electron pathway in the oxygen reduction reaction (2e- ORR). Herein, dual-coordination electrocatalyst structure (Co-NCNT/MXene) is proposed based on the modulation of oxygenated species adsorption by coordination microenvironment at the interface of metal nanocatalysts. The Co-NCNT/MXene achieves excellent H2O2 selectivity (95.25 %), yield (162 mg L-1h−1) and Faraday efficiency (94.81 %) for ORR, surpassing the most Co-based-electrocatalysts. In-situ EPR techniques reveal the selective *OOH desorption dynamic process on Co-NCNT/MXene. Density functional theory calculations confirm that asymmetric coordination of Co nanoparticles by oxygen-terminated Ti3C2-MXene and NCNT modulates the delocalized state of Co extranuclear electrons, resulting in a reduction of the d-band center of Co, thus turning the adsorption energy of *OOH within the Co-NCNT/MXene interface towards a path more conducive to H2O2 electrosynthesis. In-situ H2O2 generated in the ORR is applied to achieve excellent degradation of organic pollutants.