Bandgap regulation and doping modification of Ga_2- Cr Se₃ nanosheets

Ga₂Se₃, 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 Ga₂Se₃ semiconductor nanoparticles using a high temperature organic liquid phase method. Post-annealing treatment at different temperatures can not only improve the crystallinity of Ga₂Se₃ nanoparticles, but also regulate its optical band gap ranging from 2.50 to 2.80 eV. We further synthesized Ga_2- Cr Se₃ nanosheets by doping CrCl₃·6H₂O in the reaction process. By adjusting the Cr doping concentration, Ga_2- Cr Se₃ nanosheets can achieve a continuously tunable band gap in the range of 2.23 eV to 2.42 eV. Both Ga_2- Cr Se₃ nanosheets and Ga₂Se₃ nanoparticles exhibit excellent and stable photoelectric switching performance. With Cr doping, Ga_2- Cr Se₃ 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 Ga₂Se₃ 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- Cr Se₃ nanosheets have significant potential in future optoelectronic and magnetoelectric applications.