Preferential and efficient degradation of phenolic pollutants with cooperative hydrogen-bond interactions in photocatalytic process.

Phenolic pollutants as highly toxic and hazardous organics are widely generated from industrial and domestic process. Phenolic pollutants with different hydroxyl position (catechol, resorcinol, hydroquinone, phenol) were preferentially and efficiently oxidized in photocatalytic process (PC) by designing boron-doped TiO2 (B-TiO2).The key role for enhancing the photocatalytic activity of B-TiO2 was the formation of abundant Ti3+ species. The formation of Ti3+-O weakened the competitive adsorption of H2O in aqueous solution and favored the formation of cooperative hydrogen bond on the surface of B-TiO2, leading to enhanced adsorption of phenolic pollutants. The degradation rate constant of B-TiO2 (kB-TiO2) was regardless of the corresponding oxidation potential of phenolic pollutants. The kB-TiO2 for catechol in photocatalytic process was as high as 3.46 min-1, which was 18.2, 1.6 times higher than that of biodegradation and ozonation methods, respectively. Of note, the preferential removal mechanism of phenolic pollutants was elucidated by in-situ attenuated total reflectance (ATR)-IR and density functional theory calculation (DFT). The results were helpful for developing new preferential oxidation technologies in HO∙-mediated process for selectively removing low concentration but highly toxic pollutants.

Group-VIII transition metal boride as promising hydrogen evolution reaction catalysts.

Searching for alternative catalysts for hydrogen evolution reaction (HER) under acidic conditions has been a major challenge in chemistry. Herein, we demonstrate that it is now feasible to identify unprecedented transition metal boride phases that are both stable and active for HER via stochastic global potential energy surface scanning. We show that B alloying alters the most stable crystal phase from face-centered (fcc) to hexagonal close packing (hcp) for both Pd and Rh. In particular, Pd2B, the thermodynamically most stable Pd boride with the highest B content, is predicted to exhibit an ultra-high intrinsic HER activity, ∼2 orders of magnitude higher than that of Pt nanoparticles at 0 V vs. NHE. The group VIII transition metal boride thus represents a promising HER catalyst to replace conventional Pt catalysts.