Engineering an HEA/CN Schottky heterojunction with high-entropy and cocktail effects for enhanced charge separation in photocatalytic xylose oxidation

Abstract

Noble metal catalysts face multiple challenges in photocatalytic applications, including high cost, limited active sites, and insufficient stability. In contrast, high-entropy alloys (HEAs) present a promising alternative due to their distinctive high-entropy effect, lattice distortion, sluggish diffusion, and cocktail effect. In this study, a MoMnZrTmBa HEA cocatalyst was rationally designed and integrated in situ with carbon nitride (CN) to construct a Schottky heterojunction. Within this architecture, the CN substrate acts not only as a stabilizing scaffold that promotes the dispersion and exposure of HEA active sites, but also as an electron donor to modulate the electronic structure. The interfacial Schottky barrier enables directed separation and migration of photogenerated charge carriers. Meanwhile, the synergistic interactions among the multiple HEA components provide abundant active sites, substantially enhancing the photocatalytic efficiency. Notably, the optimized H/C-15 catalyst delivered outstanding performance in the selective oxidation of xylose, achieving a high xylonic acid yield of 67.86% and a CO production rate of 2534.52 μmol g⁻¹ h⁻¹. Outdoor experiments under concentrated sunlight and 30 consecutive recycling tests further demonstrated excellent structural stability and practical viability of the system. This work underscores the potential of HEAs in photocatalytic biomass valorization and provides a strategic framework for their rational design.