Promoting electrocatalytic methanol oxidation through Mn- generated oxygen vacancies on NiMn LDH/N-enriched carbon matrix

Abstract

Abstract With growing demand for renewable energy, it is urgent to develop prominent and robust transition metal electrocatalysts toward direct methanol fuel cell (DMFC). Nevertheless, the limited intrinsic activity of non-noble metal catalysts impeded their wide applications. To promote the electronic property of the non-noble metal catalysts, generating oxygen vacancies in non-noble metal catalysts could effectively modulate the intrinsic properties, resulting in significantly enhanced electrocatalytic performances. Herein, NiMn LDH/N-enriched carbon matrix with abundant oxygen vacancies (Ov-NiMn LDH/NCM) was achieved toward the methanol oxidation reaction through the simple hydrothermal approach. Remarkably, the optimal Ov-NiMn LDH/NCM exhibits outstanding methanol oxidation activity. The onset oxidation potential for methanol oxidation shifts negatively about 53 mV in comparison to Ni(OH)2/NCM. The current density activity of Ov-NiMn LDH/NCM reaches 38.4 mA·cm− 2, which is 1.6 folds than that of Ni(OH)2/NCM (24.0 mA·cm− 2) in 0.1 M KOH with 0.10 M methanol at the potential of 0.6 V vs. Ag/AgCl. The excellent performances for methanol oxidation reaction are attributed to the oxygen vacancies, which can significantly exposing the active sites and accelerate the charge transfer ability of the electrocatalysts. This work provides an effective avenue to construct the efficient and robust electrocatalysts toward methanol oxidation reaction.