Defective Nickel–Iron Layered Double Hydroxide for Enhanced Photocatalytic NO Oxidation with Significant Alleviation of NO2 Production
Xiaoyu Li,
Xiaoshu Lv,
Jian Pan,
Peng Chen,
Huihui Peng,
Yan Jiang,
Haifeng Gong,
Guangming Jiang,
Li'an Hou
Affiliations
Xiaoyu Li
Engineering Research Center for Waste Oil Recovery Technology and Equipment, Ministry of Education, Chongqing Technology and Business University, Chongqing 400067, China
Xiaoshu Lv
Engineering Research Center for Waste Oil Recovery Technology and Equipment, Ministry of Education, Chongqing Technology and Business University, Chongqing 400067, China
Jian Pan
Environmental Technology Innovation Center of Jiande, Hangzhou Bertzer Catalyst Co., Ltd., Hangzhou 310058, China
Peng Chen
Chongqing Key Laboratory of Green Synthesis and Application, College of Chemistry, Chongqing Normal University, Chongqing 401331, China
Huihui Peng
Engineering Research Center for Waste Oil Recovery Technology and Equipment, Ministry of Education, Chongqing Technology and Business University, Chongqing 400067, China
Yan Jiang
Engineering Research Center for Waste Oil Recovery Technology and Equipment, Ministry of Education, Chongqing Technology and Business University, Chongqing 400067, China
Haifeng Gong
Engineering Research Center for Waste Oil Recovery Technology and Equipment, Ministry of Education, Chongqing Technology and Business University, Chongqing 400067, China
Guangming Jiang
Engineering Research Center for Waste Oil Recovery Technology and Equipment, Ministry of Education, Chongqing Technology and Business University, Chongqing 400067, China; State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China; Corresponding authors.
Li'an Hou
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China; Corresponding authors.
Photocatalysis offers a sustainable means for the oxidative removal of low concentrations of NOx (NO, NO2, N2O, N2O5, etc.) from the atmosphere. Layered double hydroxides (LDHs) are promising candidate photocatalysts owing to their unique layered and tunable chemical structures and abundant surface hydroxide (OH−) moieties, which are hydroxyl radical (·OH) precursors. However, the practical applications of LDHs are limited by their poor charge-separation ability and insufficient active sites. Herein, we developed a facile N2H4-driven etching approach to introduce dual Ni2+ and OH− vacancies (Niv and OHv, respectively) into NiFe-LDH nanosheets (hereafter referred to as NiFe-LDH-et) to facilitate improved charge-carrier separation and active Lewis acidic site (Fe3+ and Ni2+ exposed at OHv) formation. In contrast to inert pristine LDH, NiFe-LDH-et actively removed NO under visible-light illumination. Specifically, Ni76Fe24-LDH-et etched with 1.50 mmol·L−1 N2H4 solution removed 32.8% of the NO in continuously flowing air (NO feed concentration: ∼500 parts per billion (ppb)) under visible-light illumination, thereby outperforming most reported catalysts. Experimental and theoretical data revealed that the dual vacancies promoted the production of reactive oxygen species (O2·− and ·OH) and the adsorption of NO on the LDH. In situ spectroscopy demonstrated that NO was preferentially adsorbed at Lewis acidic sites, particularly exposed Fe3+ sites, converted into NO+, and subsequently oxidized to NO3− without the notable formation of the more toxic intermediate NO2, thereby alleviating risks associated with its production and emission.
