A non-traditional biomass-derived N, P, and S ternary self-doped 3D multichannel carbon ORR electrocatalyst

Abstract

The synthesis of high-efficiency and low-cost electrocatalysts for the oxygen reduction reaction (ORR) is currently one of the main targets for the commercialization of fuel cells. In this work, a non-traditional N (5.43%), P (0.71%), and S (0.30%) ternary self-doped 3D multichannel carbon ORR electrocatalyst derived from spinach leaves is synthesized for the first time, using one-step annealing technology. The as-synthesized electrocatalyst (S-850) successfully avoids the shortcomings of traditional biomass-derived catalysts, such as those posed by solid micron-sized blocks and a lack of heteroatomic species. The advantageous properties exhibited by the electrocatalyst are mainly attributed to loose mesophyll cell space, various plant proteins, and chlorophyll. Based on the unique multichannel porous structure and ternary heteroatom doping, S-850 exhibits a higher limiting diffusion current density of 5.19 mA cm⁻² at 0.5 V, and better durability and CO/methanol tolerance than commercial 20% Pt/C (5.10 mA cm⁻² at 0.5 V) in O₂-saturated 0.1 M KOH solution. This work also includes density functional theory (DFT) calculations, which further reveal the mechanism of N, P, and S ternary self-doping in the spinach-derived ORR catalysts. Considering the availability of spinach around the world, this spinach-derived carbon material may also be extended to other areas, such as supercapacitors, sensors, and metal–air batteries.