Amorphization-Enabled Direct Z-Scheme CdSe/MoSex Heterojunction for Enhanced Photocatalysis

Organic pollutant degradation demands photocatalysts that couple efficient charge separation with strong redox capability. Direct Z-scheme heterojunction architectures fulfill these requirements and are consequently considered promising candidates. However, the rational design of such systems continues to present a major obstacle. Herein, a CdSe/amorphous MoSex (CdSe/a-MoSex) direct Z-scheme heterojunction was successfully synthesized via a simple solid-state grinding and low-temperature hydrothermal method. Within 120 min under visible-light irradiation, methylene blue (MB, 40 mg/L) was degraded to 97.3% efficiency by the CdSe/a-MoSex heterojunction, whose photocatalytic activity markedly exceeded that of pristine CdSe and a-MoSex. Intimate interfacial contact between CdSe and a-MoSex enables photogenerated carriers to separate and migrate more efficiently, underpinning the observed performance enhancement. Moreover, the suitable band alignment derived from valence-band (VB) XPS and Mott-Schottky measurements supports the formation of a direct Z-scheme charge-transfer pathway. The Z-scheme mechanism effectively inhibits electron-hole recombination while maintaining the robust oxidation and reduction capabilities of the photogenerated carriers. This study offers a straightforward approach for fabricating CdSe/a-MoSex direct Z-scheme heterojunctions for the efficient photocatalytic degradation of organic pollutants.