Synergistic engineering of step-scheme heterojunctions in silicon carbide nanocages for boosting piezocatalytic hydrogen peroxide synthesis in pure water

Efficient and sustainable synthesis of hydrogen peroxide (H₂O₂) is crucial for various industrial and environmental applications, yet conventional techniques always suffer from high energy consumption and environmental concerns. Here, we propose a strategy to boost piezocatalytic H₂O₂ production using an advanced Step-scheme (S-scheme) heterojunction formed between hexagonal silicon carbide (2H-SiC) and cubic silicon carbide (3C-SiC) polytypes, integrated in a nanocage architecture. Precise control of 2H/3C phase ratios has been accomplished by a low-temperature magnesiothermic reduction method, enabling the engineering of S-scheme heterojunctions within SiC nanocages with optimized interfacial properties. The resultant SiC catalysts deliver an impressive H₂O₂ production rate of 1323.2 μmol·g^-1·h^-1 in pure water, which surpasses the performance of many previously reported piezocatalysts, and is mainly attributed to the synergistic effect between heterojunctions and nanocage configuration. It is verified that the 2H-SiC phase contributes strong piezoelectric polarization, while the built-in electric field (BIEF) enabled by 2H-/3C-SiC heterojunctions facilitates effective charge separation, thus promoting efficient redox reactions. Moreover, the unique nanocage architecture optimizes the stress distribution to further enhance piezocatalytic response. This work provides a pathway for rationally designing high-performance piezocatalysts toward highly efficient and sustainable H₂O₂ production.