Facile Construction of Iron/Nickel Phosphide Nanocrystals Anchored on N-B-Doped Carbon-Based Composites with Advanced Catalytic Capacity for 4-Nitrophenol and Methylene Blue.

The search for a simple and effective method to remove organic dyes and color intermediates that threaten human safety from the water environment is urgent. Herein, we report a simple method for constructing iron/nickel phosphide nanocrystals anchored on N-B-doped carbon-based composites, using steam-exploded poplar (SEP) and graphene oxide (GO) as a carrier. The stability and catalytic activity of N-B-NixFeyP/SEP and GO were achieved by thermal conversion in a N2 atmosphere and modifying the Fe/Ni ratio in gel precursors. N-B-Ni7Fe3P/SEP was employed for the catalytic hydrogenation of 4-nitrophenol (4-NP) and methylene blue (MB), using sodium borohydride in aqueous media at room temperature. This showed much better catalytic performances in terms of reaction rate constant (0.016 S-1 and 0.041 S-1, respectively) and the activity factor, K (1.6 S-1·g-1 and 8.2 S-1·g-1, respectively) compared to the GO carrier (0.0053 S-1 and 0.035 S-1 for 4-NP and MB, respectively). The strong interaction between the carrier's morphology and structure, and the vertically grown bimetallic phosphide nanoclusters on its surface, enhances charge transfer, electron transfer kinetics at the interface and Ni-Fe phosphide dispersion on the nanoclusters, and prevents dissolution of the nanoparticles during catalysis, thereby improving stability and achieving catalysis durability. These findings provide a green and simple route to efficient catalyst preparation and provide guidance for the rational selection of catalyst carriers.