Facile hydrothermal fabrication of In(OH) 3 –RGO nanocomposites for high-performance supercapacitors

In this study, cubic-phase indium hydroxide–reduced graphene oxide (In(OH)3–RGO) nanocomposites were successfully synthesized via a one-step hydrothermal route without the need for external alkaline agents. The in-situ growth of uniformly dispersed In(OH)3 nanoparticles on conductive RGO sheets endowed the composite with a highly accessible surface area and enhanced electron/ion transport pathways. Electrochemical measurements in a three-electrode configuration revealed that In(OH)3–RGO exhibits electric double-layer capacitive behavior within the low potential window (−0.9 to 0 V), delivering a high specific capacitance of 228.9 F·g−1 at 0.5 A·g−1 and excellent rate capability, with 122.2 F·g−1 retained at 10 A·g−1. Interestingly, in the higher potential range (0.2–0.7 V), a minor Faradaic contribution was observed, leading to further enhancement of capacitance values, reaching up to 232.3 F·g−1 at 0.1 A·g−1. The synergistic effect between In(OH)3 and RGO not only improved charge storage efficiency but also effectively mitigated structural collapse during operation. These results demonstrate that In(OH)3–RGO is a promising candidate for high-performance supercapacitor electrodes, with potential advantages in dual-window energy storage systems. These results suggest that the In(OH)3–RGO composite is a promising candidate for high-performance electrode materials in advanced supercapacitor applications.