Hierarchical Co/MoO2@N-doped carbon nanosheets derived from waste lotus leaves for electrocatalytic water splitting

It is imperative for electrochemical water splitting to seek functional materials with high performance, competence, durability, economical, and eco-friendly. Herein, we develop a simplistic two-step annealing strategy to synthesize the hierarchical Co/MoO2@nitrogen (N)-doped carbon nanosheets (CMO@NC) electrocatalysts derived from the low-cost and sustainable lotus leaves biomass for water-splitting. The optimum catalyst (CMO@NC/450) exhibits a notable low overpotential of 130 and 272 mV at a current density of 10 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH, owing to their unique surface features, large surface area, abundant meso/micropores, and high pyridinic N-contents. Also, the CMO@NC/450 catalyst-equipped with a two-electrode configuration exhibits notable water splitting activity only requires a cell-potential of 1.629 V@10 mA cm−2 in 1.0 M KOH. The results reveal that hierarchical flower-like morphology increases the contact area, prevents aggregation, and enables massive active-sites for HER and OER. Additionally, the synergistic effects between Co/MoO2 and the N-doped-carbon heterostructure enhance charge-delocalization, ultimately improving electrocatalytic performance and stability. This work is aimed to promote the exploration and design of suitable doping structures and compositions for the development of highly effective and sustainable biomass-derived catalysts in a wide-range of electrochemical applications.