CoP/Co2P heterostructures embedded in biomass-derived carbons as efficient electrocatalysts for hydrogen and oxygen evolution reactions.

The development of efficient and cost-effective bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is critical for sustainable energy conversion. In this study, cobalt phosphide-based nanocomposites were synthesized via a simple hydrothermal and phosphidation process, using biomass-derived porous carbon as a sustainable support. Peanut-shell extract-derived carbon (BC) and activated carbon (AC) were used as carbon supports to obtain the CoP/Co2P@BC and CoP/Co2P@BC@AC composites. Two types of novel heterostructures were fabricated: CoP/Co2P@BC and CoP/Co2P@BC@AC. However, the optimized CoP/Co2P@BC@AC catalyst demonstrated outstanding bifunctional electrocatalytic performance, requiring overpotentials of only -227 mV for the HER and 303 mV for the OER to achieve a current density of 10 mA cm-2. Furthermore, it exhibited Tafel slopes of 121 mV dec-1 and 101 mV dec-1 for HER and OER, respectively, along with excellent long-term durability, confirming its high efficiency for overall water splitting under alkaline conditions. The outstanding catalytic behavior was mainly ascribed to the amorphous framework, large active surface area, and enhanced charge-transfer capability of the catalyst. These findings underscore the potential of biomass-derived carbon as a platform for fabricating stable, low-cost, and efficient bifunctional electrocatalysts for water-splitting applications, fostering environmentally benign energy technologies.