| Abstract:The development of efficient and durable oxygen reduction and oxygen evolution reaction (ORR/OER) catalysts is crucial for next-generation energy technologies, but still remains challenge. In this work, a wood-derived bifunctional catalyst (CoHNC) with Co-N active sites is prepared via a simple Lewis acid hydrothermal pretreatment and followed by a high-temperature pyrolysis. The physicochemical structures and electrochemical properties of CoHNC are investigated. Lewis acids can partly hydrolyze the cellulose and hemicellulose in the wood, resulting in abundant nanopores; and a high specific surface area of 1008.02 m2 g-1. Metal atoms coordinate with the oxygen-containing functional groups during hydrothermal pretreatment, and then convert into Co-N active sites after pyrolysis. The hierarchical pore structure of CoHNC facilitates the efficient diffusion of electrolyte/oxygen and the exposure of high-density active sites. The Co-N sites can effectively regulate the microenvironment of the catalyst, and thus improve the catalytic performance. CoHNC presents excellent ORR and OER activities with a positive half-wave potential of 0.869 V vs. RHE in 0.1 M KOH solution, a OER overpotential of 274 mV at a current density of 10 mA cm-2 and a ΔE of only 0.635 V, which outperform those of commercial Pt/C and RuO2. |