Electron spin-states reconfiguration induced by alternating temperature gradient for boosting photocatalytic hydrogen evolution on hollow core-shell FeS2/CuCo2O4 Z-scheme heterostructure

The pyroelectric effect and electron spin-state reconfiguration play a critical role in photocatalysis but are seldom investigated. This work is the first to exploit the fluctuating temperature (Δ T ) between the cold-hot alternation in photocatalysis to drive the pyroelectric effect and electron spin-sate reconfiguration. FeS 2 /CuCo 2 O 4 (FS/CCO) hollow core-shell heterojunctions were prepared using hydrothermal and heating treatment methods. The FeS 2 (FS) can generate heat under near-infrared (NIR) light to provide the elevated temperature end required for the pyroelectric effect of CuCo 2 O 4 (CCO) under the influence of Δ T . With this thermoelectric and pyroelectric effect, CCO can release surface charges, generating spontaneous polarization, changing the electron (e g ) filling number on Co surface sites, reversing the spin electron state, thus controlling the carriers' migration direction and enhancing their separation and migration rate, and finally prolonging their lifetime. As a result, the as-designed FS/CCO-15 composites yielded up to 19.5 mmol g −1 h −1 extraordinary photocatalytic performance, i.e., 10.2 and 6.45-fold of the pure FS (1.92 mmol g −1 h −1 ) and CCO (3.02 mmol g −1 h −1 ) under simulated sunlight, respectively. It also yielded up to 19.8% average apparent quantum yield. This work thoroughly explored the distinctive impact of the pyroelectric effect, electron spin-state reconfiguration, orbital coupling effect, and hydrogen evolution, guiding us and creating more possibilities for photocatalytic technology and efficiency using NIR light.