Bifunctional rGO/CoWO₄ nanocomposites for sustainable photocatalysis and hydrogen evolution reaction

The reduced graphene oxide (rGO)-supported cobalt tungstate (CoWO
4
) nanocomposite (rGO/CoWO
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-NC) was synthesized via a hydrothermal process for photocatalytic and electrocatalytic investigations. The prepared nanocomposites were initially characterized for phase analysis using standard analytical techniques. Thereafter, the rGO/CoWO
4
-NC materials were employed as photocatalysts in methylene blue (MB) dye degradation reactions under visible light irradiation, achieving ∼95% degradation within 2 h. After photocatalysis, the catalyst was recovered via a batch process and reused in electrocatalytic studies. Prior to use as an electrocatalyst, the recovered rGO/CoWO
4
-NC was further characterized for phase purity and stability. The recovered nanocomposite exhibited promising electrocatalytic performance for hydrogen evolution reaction (HER), with experimentally determined Tafel slope of ∼108 mV/dec and ∼88 mV/dec for the recovered and fresh catalysts, respectively. This study also highlights the potential for recycling inorganic solid waste in multifunctional applications.