Investigation of Mn2+-Dopants induced crystal defects in photoactive CuSe Nanosheets for enhanced visible-NIR range absorption and natural solar driven photocatalysis

Abstract

Limited light absorption and inefficient charge separation remain key challenges in achieving effective natural solar-driven photocatalysis using low-bandgap CuSe nanosheets (NSs). Introducing crystal defects within a certain concentration range has been recognized as an effective strategy to tackle these issue, and to design a high performance photocatalyst. Herein, Mn²⁺ is uniformly incorporated into the CuSe lattice, inducing crystal defects, resulting in efficient natural solar spectrum-driven photocatalysis. Photoluminescence (PL) spectroscopy reveals a systematic broadening in the full width at half maximum (FWHM) of defect-related emissions with increasing Mn-dopants concentration, indicating the formation of defect states. Meanwhile, the conventional absorption spectrum indicates that without sacrificing the band gap, Mn-doped CuSe NSs exhibit improve visible and NIR-1 range absorption compare to undoped CuSe NSs. The photocatalytic performance investigations, using methylene blue (MB) as a model dye, demonstrates a significant performance improvement. The results gives that CuSe NSs with 9% Mn-doping show 100% degradation with a degradation rate constant of 0.07 min-1, approximate 2 times of that of undoped CuSe NSs. This significant improvement in degradation efficiency strongly suggests that Mn-induced crystal defects, hold significant promise for effectiveness of CuSe NSs for natural solar spectrum driven photocatalysis.