Flash Joule Heating Synthesis of Nitrogen‐Rich Defective G‐C₃N₄ for Highly Efficient Photocatalytic Hydrogen Evolution

Abstract Seeking renewable energy solutions that are sustainable and environmentally friendly is a critical contemporary research imperative. This paper presents a flash Joule heating approach to prepare high‐performance nitrogen‐rich defective graphitic carbon nitride (g‐C₃N₄) for hydrogen production by photocatalytic water splitting at ultralow cost. By leveraging the rapid heating and cooling capabilities of flash Joule heating, and using melamine as the sole precursor, defects are introduced and precisely regulated while preserving the structural integrity of as‐synthesized prepared g‐C₃N₄. By tuning the processing parameters, the band structure of g‐C₃N₄ can also be optimized, which can significantly suppress electron‐hole recombination and substantially enhance its photocatalytic hydrogen evolution from splitting water. As a result, a hydrogen evolution rate of 16936.5 µmol h⁻¹ g⁻¹ for Pt/g‐C₃N₄ is achieved, which is comparable to the leading benchmarks in the field. Through a life cycle assessment (LCA) and a cradle‐to‐gate techno‐economic assessment (TEA), this method reduces costs to 1/12, energy consumption to 1/23, and CO₂ emissions to less than 1/8 of those associated with the thermal polymerization approach under equivalent conditions. These results underscore the exceptional advantages of the developed method in cost‐effectiveness and environmental sustainability, offering a robust scientific foundation for the industrial‐scale production of g‐C₃N₄‐based photocatalysts.