Highly efficient photocatalytic nitrogen fixation on bio-inspired triphase interface with improved diffusion of nitrogen

Low solubility and slow diffusion of nitrogen (N-2) in water are significant impediments for enhancing the efficiency of fixation nitrogen into ammonia (NH3). Herein, we have prepared bio-inspired hierarchical assembly of carbonized loofah sponge@BiOBr-OV/Au (CL@BiOBr-OV/Au) to improve diffusion of nitrogen by immobilization of hydrophilic BiOBr-OV/Au onto hydrophobic CL sponge. The hydrophobic CL sponge provides an optimized directional channel for N-2 diffuse to the triphase interface N-2 (gas)-H2O (liquid)-BiOBr-OV/Au (solid), which supplies generous N-2 for the photocatalytic reaction and replaces the slow diffusion of N-2 through the liquid phase. Continuous delivery of N-2 can effectively capture generated electrons, thereby preventing the recombination of generated electron-hole and promoting N-2 activation. The modification of AuNPs can broaden the photoresponse range of BiOBr-OV, increase oxygen vacancies concentration and enhance N-2 adsorption and activation. CL@BiOBr-OV/Au shows an impressive in nitrogen fixation performance with high selectivity and recyclability of 2.64 mmol.g(cat)(-1).h(-1), that is 10.2 and 8.0 times compared to CL@BiOBr-OV and BiOBr-OV/Au, respectively. Our work affords a convenient method for the construction of bio-inspired triphase catalysts with a directional N-2 transport channel to enhance the efficiency of nitrogen fixation, which also holds great promise for the application in other reactions involving gas consumption.