Bandgap regulation and doping modification of Ga 2- x Cr x Se 3 nanosheets.

Ga 2 Se 3 , an important direct wide bandgap semiconductor with excellent optoelectronic properties, has wide application potential in the fields of photodetectors, photoelectric sensors and solar cells. Herein, we describe the synthesis of Ga 2 Se 3 semiconductor nanoparticles using a high temperature organic liquid phase method. Post-annealing treatment at different temperatures can not only improve the crystallinity of Ga 2 Se 3 nanoparticles, but also regulate its optical band gap ranging from 2.50 to 2.80 eV. We further synthesized Ga 2- x Cr x Se 3 nanosheets by doping CrCl 3 ·6H 2 O in the reaction process. By adjusting the Cr doping concentration, Ga 2- x Cr x Se 3 nanosheets can achieve a continuously tunable band gap in the range of 2.23 eV to 2.42 eV. Both Ga 2- x Cr x Se 3 nanosheets and Ga 2 Se 3 nanoparticles exhibit excellent and stable photoelectric switching performance. With Cr doping, Ga 2- x Cr x Se 3 exhibits reduced Nyquist impedance and enhanced electrocatalytic activity, which is attributed to its ultrathin nanosheet morphology and large specific surface area. In addition, the diamagnetic behavior of pure Ga 2 Se 3 changes to ferromagnetism with different Cr doping concentrations, and its magnetization is as high as 18.0 emu g -1 at x = 0.4. These findings demonstrate that Ga 2- x Cr x Se 3 nanosheets have significant potential in future optoelectronic and magnetoelectric applications.