Uranium capture by a layered 2D/2D niobium phosphate/holey graphene architecture via an electro-adsorption and electrocatalytic reduction coupling process

• Published in: Journal of hazardous materials Vol. 442; p. 130054
• Main Authors: Liao, Yun, Lei, Ruilin, Weng, Xiaofang, Yan, Chuan, Fu, Jiaxi, Wei, Guoxing, Zhang, Chen, Wang, Meng, Wang, Hongqing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-01-2023
• Subjects: Electro-adsorption; Electrocatalytic reduction; Grapheme; Niobium phosphate; U(VI); U(VI); Niobium phosphate; Electrocatalytic reduction; Grapheme; Electro-adsorption
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2022.130054

As an energy-efficient and eco-friendly technique, capacitive deionization (CDI) has shown great potential for uranium (U(VI)) capture recently. However, extracting U(VI) with high kinetics, capacity and selectivity remains a major challenge due to the current surface active sites-based material and co-existing ions in aqueous solution. Here we rationally designed a layered 2D/2D niobium phosphate/holey graphene (HGNbP) electrode material, and originally demonstrated its efficient U(VI) capture ability via an electro-adsorption and electrocatalytic reduction coupling process. The less-accumulative loose layered architecture, open polycrystalline construction of niobium phosphate with active phosphate sites, and rich in-plane nano-pores on conductive graphene nanosheets endowed HGNbP with fast charge/ion transport, high electroconductivity and superior pseudocapacitance, which enabled U(VI) ions first to be electro-adsorbed, then physico-chemical adsorbed, and finally electrocatalysis reduced/deposited onto electrode surface without the limitation of active sites under a low potential of 1.2 V. Based on these virtues, the HGNbP exhibited a fast adsorption kinetics, with a high removal rate of 99.9% within 30 min in 50 mg L−1 U(VI) solution, and a high adsorption capacity up to 1340 mg g−1 in 1000 mg L−1 U(VI) solution. Furthermore, the good recyclability and selectivity towards U(VI) were also realized.
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•A layered 2D/2D sheet to sheet HGNbP electrode was rationally designed.•HGNbP exhibited a removal rate of 99.9% in 30 min and capacity up to 1340 mg g−1.•The mechanism involves electro-adsorption, electro-reduction and coordination.•The method is energy-efficient, eco-friendly, and applied a low potential of 1.2 V.