Plasma-assisted fabrication of ultra-dispersed copper oxides in and on C-rich carbon nitride as functional composites...

Significant efforts have been continuously devoted to the mastering of green catalysts for the oxygen evolution reaction (OER), whose sluggish kinetics prevents a broad market penetration of water splitting as a sustainable route for large-scale hydrogen production. In this extensive scenario, carbon nitride (CN)-based systems are in focus thanks to their favorable characteristics, and, whereas graphitic CN has been largely investigated, the potential of amorphous carbon nitride (a-CN) systems remains almost entirely unexplored. In this regard, our study presents a novel two-step plasma-assisted route to a-CN systems comprising ultra-dispersed, i.e. "quasi-atomic" CuO (x = 1, 2). The target materials were fabricated using an original strategy consisting in the magnetron sputtering of a-CN on conducting glasses at room temperature, followed by functionalization with low CuO amounts by radio frequency (RF)-sputtering, and final annealing under an inert atmosphere. The tailoring of the CuO co-catalyst content and spatial dispersion, as well as the overall composite features as a function of preparative conditions, enabled a direct modulation of the resulting OER performances, rationalized based on the formation of p-n CuO/a-CN heterojunctions. The amenable and scalable synthesis approach underscores the practicality of this method to develop (photo)electrocatalysts synergistically integrating the advantages of both constituents, yielding low-cost, green, and stable functional platforms that could contribute to the broader adoption of sustainable energy solutions.