Ag−Au‐Bimetal Incorporated ZnO‐Nanorods Photo‐Anodes for Efficient Photoelectrochemical Splitting of Water

Abstract

Plasmonic Ag−Au/ZnO nanorods (ZNRs) based photo‐anodes were synthesized using a simple electrochemical route and were then evaluated for photoelectrochemical (PEC) activity. The amalgamation of Ag and Au nanoclusters broadens the UV‐Vis light absorption in the range of 400 nm to 650 nm. Ag−Au/ZNRs photo‐anodes had shown photocurrent density of ∼1.4 mA cm−2, at a bias of 0.75 V/SCE, which is ∼3.1 times of bare ZNRs photo‐anode. Bi‐metallic Ag−Au/ZNRs based photo‐anode shows the maximum photo‐conversion efficiency of 0.77 % at 0.5 V/SCE, under one sun illumination. Formation of hot electrons in Ag−Au/ZNRs photo‐anodes can be partly held responsible for the enhanced PEC activity. Au/Ag core/shell morphology evolves when a thin layer of Ag is loaded on Au nanoparticles. For an in‐depth analysis on Ag−Au incorporated ZNRs based photo‐anodes and its PEC activity, a detailed characterization was carried out using physico‐chemical, spectral and microscopy techniques. The analysis shows that Au in direct contact with ZnO interacts mainly with oxygen vacancies present on surface of ZnO and Ag interacts with Au for an effective electron‐hole segregation process at their interface and electron storage occurs in metal nanoparticles. The results suggest bi‐metal incorporated ZNRs based photo‐anodes can be a prospective candidate for PEC water splitting application.

Optimization and Modulation Strategies of Zinc Oxide-based Photoanodes for Highly Efficient Photoelectrochemical Water Splitting

“…95 Sharma et al synthesized a bimetal system of Au−Ag as plasmonic antenna for ZnO nanostructures, leading to a 40% enhancement in the photocurrent density than that of Au-decorated ZnO photoanodes. 104 This study paves an efficient pathway for the dual metallic nanoparticle-modifying method, which is favorable to reduce the usage amount of the noble metal, and at the same time, much higher PEC performance also can be obtained.…”

“…Recently, Li et al have prepared a Cu-modified ZnO nanostructure through the magnetron sputtering method, achieving much higher photocurrent density than the pristine ZnO photoanodes, which originates from the light absorption ability enhancement in the UV–visible region and carrier separation transport improvement . Sharma et al synthesized a bimetal system of Au–Ag as plasmonic antenna for ZnO nanostructures, leading to a 40% enhancement in the photocurrent density than that of Au-decorated ZnO photoanodes . This study paves an efficient pathway for the dual metallic nanoparticle-modifying method, which is favorable to reduce the usage amount of the noble metal, and at the same time, much higher PEC performance also can be obtained.…”

Tunable Plasmon-Induced Charge Transport and Photon Absorption of Bimetallic Au–Ag Nanoparticles on ZnO Photoanode for Photoelectrochemical Enhancement under Visible Light

“…Photoelectrochemical (PEC) water splitting has been widely explored as a viable solar-to-chemical pathway by oxidizing/reducing H 2 O molecules with photogenerated electron–hole pairs in semiconductors. However, the development of an efficient semiconductor-based photoanode for water splitting is hindered by low light absorption and fast charge carrier recombination. , Therefore, MNPs have been integrated with the semiconductor to increase the photon absorption and charge carrier separation by pinning electrons at their Fermi energy level. − For instance, Au NPs and Ag NPs have been extensively integrated with semiconductors to enhance and extend the photon absorption into the visible spectrum, as well as initiating the formation of Schottky barrier at the nanoparticle–semiconductor interface to prevent charge carrier recombination. − To date, PEC studies revolving Au/Ag BNPs − have been focusing on their optical contribution, showing tunable LSPR peaks based on the composition ratio. , To the best of our knowledge, the contribution of plasmon-induced charge separation and electrical conduction on PEC performance by Au/Ag BNPs of various compositions have not been previously reported.…”

A solar-responsive zinc oxide photoanode for solar-photon-harvester photoelectrochemical (PEC) cells

“…ZnO is known to be one of the most efficient and stable UV-active photocatalysts useful for watersplitting and pollutant-remediation in its particulate form as well as in the PEC cell conguration. [22][23][24][25][26][27][28] However, its solar photocatalytic activity and PEC applicability have suffered due to its wide band gap (E g $ 3.2 eV). This demands enhancing the photon-lattice interaction in ZnO lms, which can potentially be realized via various strategies, such as control of lmsurface/structure design, surface state density or by interface engineering.…”