Magnetic Co/TiB2 for Efficient Catalytic Hydrogen Production from Ammonia Borane and Tandem Degradation of Organic Pollutants at Room Temperature

TiB2 support was prepared by molten salt method and Co/TiB2 magnetic recyclable nano-catalyst was prepared by simple precipitation - deposition method, which was used for catalytic hydrogen evolution in ammonia borane (NH3BH3) solution at room temperature and synergistic degradation of p-nitrophenol (4-NP) and azo dye such as acid orange 7 (AO7), acid red 1 (AR1), methyl orange (MO), without light, heat, other external energy, and additives. The catalyst was characterized by X - ray diffraction, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy, vibrating sample magnetometer, and other characterization methods. The results showed that Co nanoparticles were uniformly distributed on the surface of TiB 2 support, and the grain size was about 40 nm, which was coated by TiB2 support with a typical strong metal-support interaction. Co/TiB2 exhibited excellent catalytic activity for hydrogen evolution from NH3BH3 solution at room temperature, with a rate of hydrogen evolution at 565.8 mol(H2 ). mol(cat)(-1). h(-1). In the cascade reaction of degrading organic pollutants, 4 - NP amination was catalyzed by Co/TiB2 with nearly 100% conversion within 7 min, and the reaction rate constant was up to 0.72 min(-1). The reaction rate constant of degrading AO7 was the highest among the three azo dyes (0.34 min(-1)) A large number of hydrogen radicals (center dot H) was detected in the catalytic system of Co/TiB2/NH3BH3 by EPR-DMPO (EPR=electron paramagnetic resonance, DMPO=5,5-dimethyl-1-pyrroline N-oxide) free radical capture experiment. Due to the strong reducibility of center dot H radical, the catalytic system of Co/TiB2, can aminate 4 -NP into p-aminophenol (4-AP) and reduce the azo chromogen group (-N=N-) in azo dye molecules. At the end of the reaction, !he catalyst could be recycled by introducing an external magnetic field to avoid secondary pollution to the water body.

Automated summary

TiB2 support and Co/TiB2 magnetic recyclable nano-catalyst were prepared for catalytic hydrogen evolution and synergistic degradation of pollutants. The catalyst showed excellent catalytic activity and recyclability without the need for external energy sources or additives.