In Situ Growth Of Pd Nanosheets On G-C₃N₄ Nanosheets With Well-contacted Interface And Enhanced Catalytic Performance For 4-nitrophenol Reduction

Noble metal ultrathin nanosheets have unique physical,chemical and electronic properties and are widely used in catalysis.However,their high cost and low stability limit their application.Loading noble metal ultrathin nanosheets on a nanosheet support can enhance their catalytic activity and stability.The intimate interfacial contact between the two nanosheets plays a crucial role in improving catalytic performance.However,the rough and curved surface of the nanosheets makes it difficult to construct a well-contacted interface.Therefore,it is challenging to prepare a supported nanosheet catalyst with a close contact interface.In this paper,Pd nanosheets(Pd NSs)are loaded onto graphite carbon nitride nanosheets(CNNSs)by in-situ growth method.This method overcomes the limitations of nanosheet morphology incompatibility and prepares a supported nanosheet catalyst with close contact interface(Pd NSs/CNNSs).Carbon monoxide(CO)is used as reducing agent and surface confining agent.The Pd precursor is first reduced by CO and nucleated on CNNSs to form Pd nanoparticles.Under the CO-confined effect,Pd nanoparticles grow and fuse to form Pd NSs.The nitrogen-rich nature of CNNSs provides a large number of coordination sites for Pd NSs,enhances the interaction between CNNSs and Pd NSs,and improves the stability of Pd NSs.The synthetic effects of intimate contact and coordination optimize the electronic structure of Pd NSs.The binding energy for Pd 3d5/2 of Pd NSs prepared by in situ growth is shifted by 0.3 eV compared to unsupported Pd NSs.After the optimized electronic structure of Pd NSs is verified,Pd NSs/CNNSs are used to catalyze the reduction of 4-NP by sodium borohydride.Pd NSs/CNNSs exhibit significantly enhanced catalytic activity and stability.The concentration-normalized rate constant is 3052 min-1 g-1 L,which is 5.4 times higher than that of the unsupported Pd NSs.After six runs of the recycling experiments,there is no significant decrease in catalytic activity.In addition,Pd NSs have attracted great attention due to their application in photothermal therapy.However,their photodynamic properties have not been reported.Here,an anisotropic oxidation etching method is developed to introduce one-dimensional nanoholes with active crystal faces on the Pd NSs.In addition to inheriting the high photothermal conversion efficiency of Pd NSs,the prepared hole-Pd NSs(H-Pd NSs)can activate oxygen to singlet oxygen and catalyze the decomposition of hydrogen peroxide to O2.This work provides some ideas for introducing active facets in metallic pore walls,broadening the application of Pd NSs and designing multifunctional single nanomaterials for cancer therapy.