Self-template-oriented synthesis of lead-free perovskite Cs_(3)Bi_(2)I_(9) nanosheets for boosting photocatalysis of CO_(2) reduction over Z-scheme heterojunction Cs_(3)Bi_(2)I_(9)/CeO_(2)

Lead halide perovskite (LHP) nanocrystals have been intensely studied as photocatalysts for artificial photosynthesis in recent years.However,the toxicity of lead in LHP seriously limits their potential for widespread applications.Herein,we first present the synthesis of 2D lead-free halide perovskite (Cs_(3)Bi_(2)I_(9)) nanosheets with self-template-oriented method,in which BiOI/Bi_(2)O_(2) nanosheets were used as the template and Bi ion source simultaneously.Through facile electrostatic self-assembly strategy,a Z-scheme heterojunction composed of Cs_(3)Bi_(2)I_(9)nanosheets and CeO_(2) nanosheets (Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1) was constructed as photocatalyst for the photo-reduction of CO_(2) coupled with the oxidation of H_(2)O.Due to the matching energy levels and the close interfacial contact between Cs_(3)Bi_(2)I_(9)and CeO_(2) nanosheets,the separation efficiency of the photogenerated carriers in Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1 composite was significantly improved.Consequently,the environment-friendly halide perovskite heterojunction Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1presents impressive photocatalytic activity for the reduction of CO_(2)to CH_(4)and CO with an electron consumption yield of 877.04μmol g^(-1),which is over 7 and 15 times higher than those of pristine Cs_(3)Bi_(2)I_(9)and CeO_(2)nanosheets,exceeding the yield of other reported bismuth-based perovskite for photocatalytic CO_(2)reduction.

In-situ growth of PbI_(2) on ligand-free FAPbBr_(3) nanocrystals to significantly ameliorate the stability of CO_(2) photoreduction

Excellent optical properties involving strong visible light response and superior carrier transport endow metal halide perovskites(MHP)with a fascinating prospect in the field of photocatalysis.Nevertheless,the poor stability of MHP nanocrystals(NCs)in water-contained system,especially without the protection of long alkyl chain ligands,severely restricts their photocatalytic performance.In this context,we report an effortless strategy for the generation of ligand-free MHP NCs based photocatalyst with high water tolerance,by coating PbI_(2)on the surface of ligand-free formamidinium lead bromide(FAPb Br_(3))NCs via the facile procedure of in-situ conversion with the aid of ZnI_(2).Under the protection of PbI_(2)layer,the resultant FAPb Br_(3)/PbI_(2)composite exhibits significantly ameliorated stability in an artificial photosynthesis system with CO_(2)and H_(2)O vapor as feedstocks.Moreover,the formation of compact PbI_(2)layer can accelerate the separation of photogenerated carriers in FAPbBr_(3)NCs,bringing forth a remarkable improvement of CO_(2)photoreduction efficiency with an impressive electron consumption yield of 2053μmol/g in the absence of organic sacrificial agents,which is 7-fold over that of pristine FAPb Br_(3)NCs.