One-pot microwave synthesis of hierarchical C-doped CuO dandelions/g-C3N4 nanocomposite with enhanced photostability for photoelectrochemical water splitting

Abstract

Cupric oxide (CuO) is a semiconductor of choice for photocathode in photoelectrochemical (PEC) applications due to its great sunlight absorption capability. However, photocorrosion is the main drawback of CuO. Herein, CuO/graphitic carbon nitride (g-C3N4) with a unique microstructure, enhanced PEC performance, and considerable photostability is synthesized under microwave irradiation. A facile, one-pot method is utilized to directly deposit the nanocomposite onto fluorine-doped tin oxide from a solution containing copper precursor and urea. Possible mechanism of CuO/g-C3N4 formation through this novel method is investigated. It is elucidated that controlled amounts of urea critically determine the morphological evolution of CuO, while its excess quantities convert to g-C3N4 in the presence of CuO as the catalyst. Through an appropriate heat treatment, carbon is doped into CuO lattice. The obtained C-doped CuO/g-C3N4 demonstrates 227% enhancement over CuO in photocurrent density and ~80% photocurrent retention. The enhanced photoelectrocatalytic activity is mainly attributed to unique morphology of CuO, effective separation of charge carriers, and formation of heterojunction. These characteristics manifest the superiority of this approach over many other chemical-based methods. The nanocomposite synergistically integrates the advantages of both the constituents, offering a low-cost, efficient photocathode for PEC water splitting, photocatalytic hydrogen evolution, and degradation of pollutants.