Amidst the global environmental crisis, which is closely related to the energy-intensive production of chemicals, a possible way-out is to shift to renewable and clean processes. Photo(electro)catalysis, after the recent renaissance of the concept in the field of water splitting and synthetic organic chemistry, has proven itself to be a promising candidate for the replacement of these chemical processes. By harvesting energy from light, a milder reaction condition can be achieved, lowering the environmental impact of the reaction itself. With a constantly applied potential on the reaction system, a photoelectrocatalytic system can engage molecules that has higher redox potentials and enables reactions that were not possible. The ultimate goal is to utilise visible photons, potentially exploiting the sun radiation, which is sustainable, renewable, and abundant on the entire planet. [1]

Nitrogen fixation is one of the most important industrial process for the human society, where it also contributes to 1.4% of the global carbon dioxide emission and consumes 1% of the energy produced. [2] While most of the efforts from the scientific community focus on the direct transformation of dinitrogen to ammonia, fixation of N₂ towards high-value organic compounds only received limited attention. With nitrogen-containing organic compounds, such as azoles, pyrazines and pyridazines being important precursors of pharmaceutical products, difficulties arise from pure photocatalytic and electrolytic approaches to synthesise these molecules directly from atmospheric nitrogen. Photoelectrocatalysis, unifying the principles of photocatalysis and electrocatalysis, has presented itself as a possible solution for the activation of inert molecules. An example of the power of photoelectrocatalysis is reported by Hu and Grätzel in 2019, where they successfully achieved oxidative C–H aminations of electron-rich aromatics with haematite photoanode. [3]

Herein, we developed a facile method of fixing an activated N₂ source, hydrazine, onto diketones, under room temperature and pressure. The photoelectrode employed here is a multilayer electrode containing a photoactive graphitic carbon nitride layer. In the recent years, carbon nitride materials (CN) have gained significant attention because of its medium band-gap energy, chemical stability and relatively low-cost of synthesis, thus considered as a promising candidate to develop advanced catalytic systems active by means of visible light.