Synergistic Bulk Electronic Regulation and Interfacial Nitrate Enrichment in Polyethyleneimine–Functionalized Boron‐Containing CeO 2 for Highly Selective Photocatalytic Nitrate Reduction to Ammonia
Xuan Sun, Lijia Chen, Tianhui Yu, Haolin Zhang, Xianyan Xu, Boyang Zheng, Zheming Ni, Shengjie XiaABSTRACT
A polyethyleneimine‐functionalized boron‐containing CeO 2 composite photocatalyst (PEI@B‐CeO 2 ) was constructed. Experimental characterization and theoretical calculations jointly revealed that B incorporation provided bulk regulation by inducing local structural distortion in CeO 2 and modulating defect‐related electronic states, thereby broadening the photoresponse range and promoting photogenerated charge separation. In parallel, the PEI interfacial layer created a positively charged microenvironment through protonated amine groups and enabled the noncovalent stabilization and enrichment of NO 3 − via electrostatic attraction and charge‐assisted N–H···O hydrogen bonding. Owing to the functional complementarity between bulk electron supply and interfacial substrate capture, the optimized catalyst exhibited markedly enhanced photocatalytic nitrate reduction performance, delivering an NH 4 + production rate of 271.87 µmol g − 1 h − 1 , approximately 3.2 times that of pristine CeO 2 , together with an apparent NH 4 + selectivity of 92.85%. In situ FTIR spectroscopy identified a stepwise reaction pathway involving the conversion of NO 3 − into NH 4 + through NO 2 − and NH 2 OH intermediates, consistent with suppressed NO 2 − accumulation and enhanced deep reduction. Centrifugation‐induced interfacial perturbation experiments further showed that the evolution of catalytic activity was closely associated with changes in PEI‐derived interfacial species, while the retained PEI‐related species continued to provide a measurable interfacial contribution.