Unraveling the oxygen evolution activity of biomass-derived porous carbon plate as self-supported metal-free electrocatalyst for water splitting

Abstract

Developing the efficient and low-cost electrocatalysts derived from biomass is a desired solution to address economy and sustainability challenges of hydrogen production from water electrolysis due to utilizing metal-based catalysts. Herein, the peeled cornstalk-derived porous carbon plates synthesized by salt template-assisted high-temperature pyrolysis are utilized as self-supported metal-free electrocatalysts to unravel the oxygen evolution activity for alkaline water splitting. The resultant PC-700-10 honeycomb carbon catalyst exhibits the superior electrocatalysis for oxygen evolution owning to its high specific surface area of 52.0 ​m² ​g⁻¹, suitable micro- and meso-pores, electron-withdrawing pyridinic-N moiety and appropriate balance between hydrophilicity and electroconductivity. Theoretical calculations reveal that the largest energy barrier of forming ∗OOH limits the OER rate and ∗OH oxidation generates the energetically more favorable epoxide intermediate. This finding opens the way to construct the hopeful metal-free OER electrocatalysts via regulating their intrinsic structure, and inspires the applications of waste biomass in the energy-correlated fields.