Breaking Trade-Off between Selectivity and Activity of Nickel-Based Hydrogenation Catalysts by Tuning Both Steric Effect and d-Band Center.

For selective hydrogenation of chemicals the high selectivity is always at the expense of activity and improving both selectivity and activity is challenging. Here, by chelating with p-fluorothiophenol (SPhF)-arrays, both steric and electronic effects are created to boost the performance of cheap nickel-based catalysts. Compared with dinickel phosphide, the SPhF-chelated one exhibits nearly 12 times higher activity and especially its selectivity is increased from 38.1% and 21.3% to nearly 100% in hydrogenations of 3-nitrostyrene and cinnamaldehyde. Commercial catalysts like Raney Ni chelating with SPhF-array also exhibits an enhanced selectivity from 20.5% and 23.4% to ≈100% along with doubled activity. Both experimental and density functional theory (DFT) calculation prove that the superior performance is attributed to the confined flat adsorption by ordered SPhF-arrays and downshifted d-band center of catalysts, leading to prohibited hydrogenation of the vinyl group and accelerative H2 activation. Such a surface modification can provide an easily-realized and low-cost way to design catalysts for the selective hydrogenation.