Amorphous boron phosphide nanosheets: A highly efficient capacitive deionization electrode for uranium separation from seawater with superior selectivity

Boron phosphide nanosheets were synthesized by direct chemical reaction of B2H6 and PCl3 at ambient temperature, facilitated by use of plasma in an ionic liquid. The material possessed excellent specific capacity of 179.3 F g−1, large specific surface area (221.7 m2 g−1), and an average thickness of 8.422 nm. It can serve as an electrode material for capacitive deionization to extract U(VI) ions from aqueous solution at concentrations ranging from 0.05 to 130 mg L−1, with a maximum adsorption capacity of 2584 mg g−1. The excellent performance of these boron phosphide nanosheets is mainly due to their special structural features and ability to strongly coordinate with uranium, which facilitates the electrosorption process. This material also demonstrated superior selective adsorption characteristics for U(VI) ions over other competing metal ions (Sr2+, Ba2+, VO3−, Cr3+, Ca2+, Co2+, Cu2+, Mn2+, Mg2+, Ni2+, Fe3+, Na+, and K+) present in natural seawater. Boron phosphide nanosheets offer potential as a novel and potent electrode material to extract uranium from seawater using capacitive deionization technology.