Effective coupling of Cu (II) with BiOCl nanosheets for high performance electrochemical supercapacitor and enhanced photocatalytic applications

A facile solvothermal route is developed to prepare ultrathin Cu (II) modified BiOCl nanosheets for promising photocatalytic and electrochemical energy storage applications. The modification of BiOCl nanosheets with Cu (II) significantly enhanced the photocatalytic activity for degradation of methyl orange dye (MO) and electrochemical energy storage in symmetric supercapacitor. The amount of Cu (II) on BiOCl nanosheets was optimized by meticulously controlling the Cu (II) loading as 2, 4, 6 and 8 wt% to achieve the best possible photocatalytic activity. The crystalline nature, elemental composition, morphology and optical properties of prepared nanosheets are studied in detail using XRD, XPS, TEM and UV–vis spectroscopy analyses, respectively. The catalyst prepared with 6 wt% Cu (II) loading performed the best performance with 97% of MO degradation at 10 mg/L (0.03 mM) MO dye concentration within 50 min in visible light. The high activity was attributed to the increased surface area of the catalyst from 22 to 43 m² g⁻¹ upon Cu (II) over ultrathin BiOCl nanosheets. Also, the Cu (II) modification, permitting adsorptions of more number of active species and could help in restricting the recombination rate by allowing easy transit of excited electrons to Cu (II). Also, a highly stable performance is achieved when it was reused for five times. The BiOCl and Cu (II) modified BiOCl nanosheets with different Cu loading were studied for electrochemical supercapacitor application. The 6 wt% Cu (II)/BiOCl showed a high specific capacitance of 155 F/g with high specific capacitance retention of 101% after 5000 cycles.