Surface Plasmon Resonance Enhancement Of Catalytic Activities Based On Metal Nanostructure

Surface plasmon resonance?SPR?effect of noble metal nanostructure is one of the most widely known strategies to enhance the light absorption,photon to electron conversion efficiency and light enhanced catalytic activity of catalysts or catalytic electrodes.The application of the SPR effect of noble metal nanostructures on the enhancement of photon to electron conversion efficiency and photocatalytic activity are still restricted by some issues,such as,the energy loss and recombination on the transmission of hot carries which are generated from the noble metal nanostructures SPR effect.Many researches indicate that the separation of hot carriers generated by the SPR effect have also be actualized by the carrier conduction medium or the energy barrier between the interface of metal nanostructure and semiconductor.The energies of hot carriers would be exhaust by the emission of photon or heat during the long transmission in carrier conduction medium.For metal-semiconductor heterostructures,the hot electrons with the energies higher than that the barrier energy can be permite injected into the semiconductor.Therefore,it is extremely urgent to find a new strategy to solve the problems of the electron-hole pairs efficiency separation and the direct utilization of hot carriers in photocatalytic.In this work,the direct utilization of hot carriers on noble metal nanostructures SPR for the enhancement of photocatalytic H₂O₂ generation,methanol oxidation reaction?MOR?and photovoltaic response have been investigated.The Ag NP/SG/Cu nanosandwich structure was formed by depositing Ag NPs on the surface of a two-dimensional single layer graphene with Cu contacts using ion-sputtering method.The photocatalysis H₂O₂ generation of Ag NP/SG/Cu was investigated,the schematic of band diagram and electron-hole pairs separation of Ag NP/SG/Cu have also been studied.The photoelectronic responses of Ag NP/SG/Cu-120s present in photocurrent is-15.8?A cm^-2,which has a zero-phase angle related to the induced photovoltage of 17.5 m V cm^-2.By performing the photocatalysis H₂O₂ generation on Ag NP/SG/Cu,a yield of H₂O₂ is 229.33?M after 6 h in O₂ saturated aqueous solution under simulated solar illumination.The XPS results indicate that the separation of hot electron-hole pair from Au SPR is dependant on the built-in field of Ag NP/SG/Cu nanosandwich structure.Theses results indicate that the hot electrons can be utilized directly for ORR on the surface of Ag NPs.The ion-sputtering method was utilized to synthesize gold caviar-like assembly?Au-CA?on the surface of glass carbon,and the SPR-enhanced MOR catalytic activity and stability of Au-CA were investigated.The Au-CA achieved anodic peak current of 248.9?A?g^-1 under irradiation,which was about twice higher than that in the dark(115.86?A?g^-1).The results of XPS spectra indicate that the electronic structure of Au-CA exhibited no obvious change under simulated solar irradiation in comparison with those in dark.The results of photocurrent response present that Au-CA achieved a photocurrent density of 175.8?A?g^-1 at a 468 nm light-emitting diode?LED?irradiation,which is 2.5 times higher than that of at 640 nm(70.2?A?g^-1).Regarding electrochemical stability,the electrooxidation current density of Au-CA was notably higher under simulated solar irradiation(51.2?A?g^-1)than under dark conditions(16.5?A?g^-1),even after the reaction duration was extended to 40 min.The Au-n/SG/Cu nanosandwich structure for the catalysis of MOR was fabricated by the ion-sputtering method.The strong metal-graphene interaction and the Au NP SPR direct effect on the MOR catalytic activity of Au-6T/SG/Cu were studied.The cyclic voltammogram?CV?tests results revealed that the Au-6T/SG/Cu achieved a forward anodic peak current of 287.65?A?g^-1toward MOR under simulated solar irradiation,which was approximately 1.72-fold greater than that of without irradiation(166.82?A?g^-1).In addition,results of photocurrent response and CV tests under various light irradiations displayed that Au-6T/SG/Cu achieved a photocurrent density of 233.68?A?g^-1,and the anodic peak current density towards MOR exhibited a significant enhancement under a 565 nm LED light irradiation.The results of DFT calculation present that the OH^-adsorption energy of metallic Au in Au-n/SG/Cu can be enhanced from-1.896 to-3.273 e V.These results indicate that the adsorption of OH^-and formation of·OH radicals on Au surface plays the important roles in the enhancement of MOR activity on Au-6T/SG/Cu.High-quality vertically aligned ZnO nanorod arrays on FTO glass were grown by electrochemical deposition synthesis method in a 90?water bath.Subsequently,the Ag NPs/ZnO NRs/FTO heterostructure was prepared by depositing Ag NPs on the surface of ZnO nanorods using ion-sputtering method.The TEM results show that the length of ZnO nanorod is increased with the increasing of reaction time when the electrodeposition time is less than40 min,but the long electrodeposition time will induce the dissolution of ZnO nanorod.The results of diffuse reflectance UV-vis absorption spectra indicate that the energy gap of ZnO NRs/FTO is 3.36 e V,and the absorption property of Ag NPs/ZnO NRs/FTO in visible light region can be enhanced by the SPR of Ag NPs.The results of photoelectrochemical present that the largest photocurrent,open voltage and short current of Ag NPs/ZnO NRs/FTO-120s are 58.6?A cm^-2,0.85 V and 19.38?A cm^-2,respectively.