Facile synthesis of Co-doped In2O3 integrated with tubular g-C3N4 heterostructure and their synergistic effect on the enhanced photocatalytic degradation of tetracycline and oxygen evolution reaction

Abstract

In this work, we developed cost-effective and environmentally friendly bifunctional catalysts for energy and environmental applications. Tubular graphitic carbon nitrides (TCN), In2O3, In2O3/TCN, and x% cobalt (Co) doped In2O3/TCN (x = 1 %, 3 %, and 5 wt% of Co) composite materials synthesized by polymerization and hydrothermal methods. The photocatalytic activity of these materials was tested for tetracycline (TC) removal under sunlight and visible light illumination. Among them, 5 % Co-In2O3/TCN composite exhibited the highest photocatalytic efficiency, achieving 100 % and 94 % TC degradation under sunlight and visible light, respectively. PL analysis indicated that the 5 % Co-In2O3/TCN composite exhibited superior charge separation efficiency. Scavenging tests confirmed that holes (h+) and superoxide radicals (O2•−) play important roles in the photocatalytic process. The electrochemical performance of the prepared materials was investigated in 1.0 M KOH. Among the catalysts, the 5 % Co-In2O3/TCN@nickel foam (NF) composite showed the best oxygen evolution reaction (OER) performance with low overpotential (240 mV) and Tafel slope (95 mV/dec) and maintained stability for more than 24 h at 10 mA/cm2. An electrolyzer using 5 % Co-In2O3/TCN@NF||Pt/C@NF catalyst achieved cell voltages of 1.73 V and 2.23 V at 10 mA/cm² and 100 mA/cm², respectively. In this study, we developed low-cost photo and electrocatalysts that exhibited excellent environmental remediation and energy production capabilities.