Anchoring of graphitic carbon nitride on reduced graphene sheets by UV pulsed laser irradiation for augmented photoelectrochemical water splitting

Abstract

Recently graphitic carbon nitride (GCN) has gained a great significance as it is one of the most suitable materials for large-scale photocatalytic water splitting because, it has a narrow band gap energy, photoelectrochemical stability, non-toxicity, and low-cost production. However, bare GCN is not reliable in terms of its relatively poor intrinsic photoelectrochemical performance as it possesses a low surface area, a high recombination rate of photo-induced charge carriers, and poor adhesion to the current collector. Here, we report a green, and low-cost approach to anchor GCN on reduced graphene oxide (rGO) sheets, forming rGO/GCN colloidal nanocomposite by simply irradiating a GO/GCN dispersion in methanol aqueous solution using a UV laser without further treatment. In contrast with the bare GCN, the synthesized rGO/GCN nanocomposite exhibited a higher tendency of visible light absorption (400-700 nm), a lower recombination rate of photo-induced charge carriers, excellent adhesion on the current collector, and thus higher photoelectrochemical efficiency for water splitting under visible light illumination. The photocurrent density of the rGO/GCN photoanode was enhanced by nine folds (~90 mA cm−2) in alkaline media over that one produced by the bare GCN under the same operating conditions. This study exhibits the feasibility and effectiveness of UV laser irradiation in the synthesis of high-purity rGO-based photocatalytic nanocomposites at room temperature for large-scale photoelectrochemical water splitting.