Nickel-Modified Carbon Nitride for Enhanced Photocatalysis

The development of efficient artificial photocatalysts is a promising strategy for addressing global energy and environmental challenges. Polymeric carbon nitride (CN) has emerged as a strong candidate for photocatalytic hydrogen (H₂) evolution due to its favorable electronic structure and ease of synthesis. However, its performance is limited by the rapid recombination of photogenerated charge carriers. To overcome this limitation, CN was synthesized through the thermal polycondensation of melamine and subsequently modified with nickel (Ni) cocatalysts through magnetron sputtering. The Ni loading was precisely tuned by adjusting the deposition time, reaching up to 0.11 wt%. A range of characterization techniques, including UV-Vis spectroscopy, FTIR, XRD, SEM, XPS, and XAS, was used to evaluate the structural and electronic properties of the CN-Ni materials. The results confirmed the presence of Ni²⁺ species, primarily as NiOx and Ni(OH)x, which contributed to the improved charge separation by acting as hole and electron scavengers. Additionally, the incorporation of Ni led to modifications in the nitrogen bonding states without altering the bulk structure of the CN. These changes correlate with enhanced photocatalytic activity, supporting a proposed mechanism based on the interaction between CN and different Ni species. This study provides meaningful insights into the design of non-noble-metal-based photocatalysts for sustainable hydrogen production.