Biomass Waste-Derived Electrocatalyst Constructed with g-C₃N₄ as a Multifunctional Template for Efficient Oxygen Reduction Reaction

Exploring an effective way to convert biomass waste into highly active oxygen reduction reaction (ORR) electrocatalysts will not only benefit alleviating environmental management pressure, but also open up new ways for the development of alternatives to Pt-based catalysts. Although the traditional pyrolysis conversion method has been proved to be stable and feasible, the low electrocatalytic activity of the product and the cumbersome post-treatment process make it difficult to be popularized. Here, we report an effective method to overcome the mentioned drawbacks: the introduction of g-C₃N₄. The experimental results confirm that g-C₃N₄ can be used as a multifunctional template for adjusting the morphology and providing N source. More importantly, it will decompose at 700 °C and avoid post-treatment of residues. The pyrolysis products assisted by g-C₃N₄ exhibit similar ORR performances to commercial Pt/C, including onset potential of 0.963 V (vs. RHE), half-wave potential of 0.835 V (vs. RHE) and limiting current density of 6.35 mA ⋅ cm⁻². Impressively, the product displayed outstanding performance on output power density (107 mW ⋅ cm⁻²) and discharge performance at different current densities as the air electrode of zinc-air battery, which even superior to that of commercial Pt/C. This study elucidated the functional role of g-C₃N₄ in reaction system and facilitated the development of more efficient biomass waste-based ORR electrocatalysts.