Origin of Bismuth-Rich Strategy in Bismuth Oxyhalide Photocatalysts

Recently,the bismuth-rich strategy via increasing the bismuth content has been becoming one of the most appealing approaches to improve the photocatalytic performance of bismuth oxyhalides.However,insights into the mechanism behind the encouraging experiments are missing.Herein,we report the results of the theory-led comprehensive picture of bismuth-rich strategy in bismuth oxyhalide photocatalysts,selecting Bi_(5)O_(7)X(X=F,Cl,Br,I)as a prototype.First-principle calculations revealed that the strategy enables good n-type conductivity,large intrinsic internal electric field,high photoreduction ability and outstanding harvest of visible light,and particularly ranked the intrinsic activity of this family:Bi_(5)O_(7)F>Bi_(5)O_(7)I>Bi_(5)O_(7)Br>Bi_(5)O_(7)Cl.Designed experiments confirmed the theoretical predictions,and together,these results are expected to aid future development of advanced photocatalysts.

A new insight into the promoting effects of transition metal phosphides in methanol electrooxidation

The construction of highly active catalysts for methanol oxidation reaction(MOR)is central to direct methanol fuel cells.Tremendous progress has been made in transition metal phosphides(TMPs)based catalysts.However,TMPs would be partially damaged and transformed into new substances(e.g.,Pt-M-P composite,where M represents a second transition metal)during Pt deposition process.This would pose a large obstacle to the cognition of the real promoting effects of TMPs in MOR.Herein,Co_(2)P co-catalysts(Pt-P/Co_(2)P@NPC,where NPC stands for N and P co-doped carbon)and Pt-Co-P composite catalysts(Pt-CoP/NPC)were controllably synthesized.Electrocatalysis tests show that the Pt-Co-P/NPC exhibits superior MOR activity as high as 1016 m A/mg_(Pt),significantly exceeding that of Pt-P/Co_(2)P@NPC(345 m A/mg_(Pt)).This result indicates that the promoting effect is ascribed primarily to the resultant Pt-Co-P composite,in sharply contrast to previous viewpoint that Co_(2)P itself improves the activity.Further mechanistic studies reveal that Pt-Co-P/NPC exhibits much stronger electron interaction and thus manifesting a remarkably weaker CO absorption than Pt-P/Co_(2)P@NPC and Pt/C.Moreover,Pt-Co-P is also more capable of producing oxygen-containing adsorbate and thus accelerating the removal of surface-bonded CO^(*),ultimately boosting the MOR performance.