Overall piezoelectric clean H₂O₂ production over metal-free bulk phase carbon-doped h-BN nanosheets

Mechanical energy-derived piezoelectric catalytic production of hydrogen peroxide (H₂O₂) is a green and attractive production route. But it is short of metal-free and hydrostable piezoelectric catalyst. In the present work, carbon-doping h-BN (h-BCN) nanosheets with thickness of about 140 nm were successfully prepared by heating phenolic resin spheres in NaNH₂ and NaBH₄ molten salts. Without complicated layer-stripping processes of h-BN, this carbon-doping strategy enabled bulk phase h-BCN powder to become responsive for piezoelectric action. With the sharper band gaps, the resultant h-BCN nanosheets were demonstrated as efficient metal-free piezoelectric catalyst for H₂O₂ production in water by 2e⁻ oxygen reduction reaction combing with water oxidation reaction route. It gives a H₂O₂ production rate of about 1109 μmol g⁻¹h⁻¹ in water under the optimized conditions, together with better long-time mechanical and hydrostable stability. Carbon-doping effect enhanced the photoinduced charge separation, migration and activation efficiency of h-BCN, attributing to its impressive pizeocatalytic H₂O₂ production performance. The generated H₂O₂ solution could be directly used to degrade dyes in water without additional Fenton catalyst. This work provides a simple and cheap carbon-doping strategy to obtain useful metal-free h-BN-based piezoelectric catalysts for producing clean H₂O₂ solution.