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Recently, Zhang Yuchao and his colleagues from the Photochemistry Laboratory of the Institute of Chemistry, Chinese Academy of Sciences, led by Zhao Jincai, made progress in the photoelectrocatalytic treatment of ammonia-nitrogen wastewater, revealing the general patterns and control principles of the bias voltage distribution in photoelectrochemical full-reduction cells. The urea oxidation reaction is an important method for treating ammonia-nitrogen wastewater in the environment, and it is also a highly studied anodic half-reaction in photoelectrochemical water splitting for hydrogen production. An efficient conversion of urea to nitrite helps to close the loop in artificial nitrogen cycles, thereby establishing a sustainable nitrogen economy. However, current research on photocatalytic urea decomposition often faces issues such as slow carbon–nitrogen bond dissociation kinetics and low product selectivity. The research team found that on the nickel oxide-modified N-type silicon photoanode surface, there is a strong attraction between trapped holes and adsorbed urea, which can induce a nitrogen-oxygen coupling process with almost no energy barrier. This, in turn, weakens the bonding strength of the carbon-nitrogen bond in urea molecules and accelerates the kinetics of urea decomposition. Quantitative results show that as the surface vacancy coverage increases from 0 to 1, the activation energy for urea decomposition decreases from 0.74 eV to 0.41 eV, resulting in an increase in the urea decomposition rate by more than two orders of magnitude. This work provides a new strategy for enhancing the photocatalytic activity of urea oxidation.