Unveiling the bi-functional potential of CoWO4 hybridized with tubular g-C3N4 for highly photocatalytic hydrogen production, water purification and supercapacitance activities

Abstract

In this paper, CoWO4 nanospheres were successfully hybridized with graphitic carbon nitride with tubular morphology (TCN) and the photocatalytic antibiotic degradation, hydrogen evolution and supercapacitor performances were examined in detail. The morphological, structural and optical properties were characterized. The hybrid CoWO4/TCN-2 catalyst showed the highest tetracycline degradation efficiency with the rate constant of 0.0198 min(-1) which was 3.73 and 5.21 times greater than that of CoWO4 and TCN samples, respectively. The rate of photocatalytic hydrogen evolution was found to be 1997 mu mol/g.h for CoWO4/TCN-2 which was 2.03-fold and 1.09-fold higher than of TCN and CoWO4 samples, respectively. Electrochemical analysis revealed that the charge storage in CoWO4, TCN, and CoWO4/TCN electrodes was mainly governed by faradaic processes. All electrodes showed high-rate capability (>85 %), coulombic efficiency (>90 %) and cycle stability (>100 %). While CoWO4 and TCN electrodes show higher redox activities and specific capacitances than CoWO4/TCN composites, this limitation is mitigated by enhanced wettability in CoWO4/TCN electrodes. Notably, the CoWO4/TCN-2 electrode exhibits superior long-term capacitance, surpassing the TCN electrode after 2000 GCD cycles. This work offers new application areas for the metal tungstate/carbon nitride photocatalysts with improved photocatalytic and electrochemical performances.