Strain and Band Modulation of <scp>WO</scp> ₃ / <scp>SnSe</scp> Micro‐Nano Composites Achieving Superior Photocatalytic Performance

SnSe, known for its narrow bandgap and visible light absorption capability, serves as a photocatalyst for environmental remediation. This work employs strain and band modulation to enhance photocatalytic performance through WO 3 /SnSe micro‐nano composite construction. Strain energy density (SED) calculations using the Williamson‐Hall method reveal substantial lattice strain in the 2.5% WO 3 /SnSe composite, reaching 83.6 J cm −3 . Combined experimental characterization and density functional theory (DFT) calculations demonstrate that strain modulation improves methyl orange (MO) adsorption energy, extends visible light absorption, and facilitates electron transfer and charge carrier separation. The optimized 2.5% WO 3 /SnSe composite achieves 99.71% MO degradation within 60 min, representing an 11.7‐fold enhancement in reaction kinetics compared to pristine SnSe. The heterostructure induces favorable band alignment that promotes the formation of and · OH active species. These findings establish strain and band modulation as viable strategies for developing high‐performance photocatalysts.