Crystalline facet-driven NiS2/CdS composites for enhanced piezoelectric photocatalytic hydrogen evolution and mechanism

Crystal plane engineering and the piezoelectric effect show promise for enhancing hydrogen evolution reaction performance, yet potential synergistic effects between them remain unclear. In this study, NiS 2 /CdS composites dominated by CdS (002) crystalline facet were successfully synthesized and used for piezoelectric photocatalytic hydrogen evolution. Under piezoelectric conditions, CdS72 with a high (002) facet ratio demonstrated a 4.56 times improvement in hydrogen evolution performance compared to pure light irradiation, while CdS24 with a lower (002) facet ratio showed a 2.8 times enhancement. Notably, the optimized sample NiS 2 -5/CdS72 reached a piezoelectric photocatalytic hydrogen evolution rate of 15.67 mmol g −1  h −1 , which is 4.54 times higher than that of NiS 2 -5/CdS24 with pure irradiation. Through piezoelectric force microscopy (PFM) and finite element simulations, we revealed that the (002) enriched CdS72 generates stronger piezoelectric fields, which synergistically accelerate photogenerated charge separation as evidenced by enhanced piezoelectric photocurrent responses. The combination of the piezoelectric effect and crystalline face engineering enables structural design and broad application of highly active photocatalysts.