Incorporation of Ag nanowires in CuWO₄ for improved visible light-induced photoanode performance

Abstract

We report the sol-gel synthesis of a CuWO 4 (E g $ 2.0-2.15 eV) thin film loaded with Ag nanowires. The incorporation of Ag nanowires into the semiconductor matrix significantly improves the performance of CuWO 4 as a photoanode for use in photochemical water splitting (PEC). Here, we have developed a planar electrode to test the photoactivity of the catalyst using standard electrochemical procedures under simulated solar light. The sol-gel synthesis of CuWO 4 is modified such that we add Ag nanowires during sol aging. We demonstrate that there is negligible change to the CuWO 4 matrix microstructure, morphology or crystal structure. When we compare the pristine CuWO 4 to the material with Ag nanowires embedded in the CuWO 4 matrix there is a fourfold improvement of photocurrent at 1.23 V vs.NHE to ca. 1.5 mA cm À2 (pH 9) under simulated AM1.5G illumination. This photocurrent is very competitive against more well developed photoanode structures when consideration for surface area is allowed. The Ag nanowires increase carrier mobility film enabling a sufficiently thick sample of catalyst, measured at 750 nm, to effectively harvest incident light. The addition of the Ag nanowires removes the plateau region found for CuWO 4 further indicating that there is a good flow of carriers to the surface of the catalyst, a significant improvement as carrier mobility has been shown to be low in CuWO 4 . The Faradaic efficiency of the catalyst was measured at 31%. Our flat band potential is found to be 0 vs. NHE.The ability to make a highly photoactive catalyst using a simple chemical process opens up opportunities in a wide range of areas that focus on PEC and other light harvesting processes.Cite this: J. Mater. Chem. A, 2015, 3, 9638

Preparation of Bifunctional CuWO4‐Based Heterostructure Nanocomposites for Noble‐Metal‐Free Photocatalysts

“…Particularly, the presence of and CuO, enhance the photocatalytic activity and photocurrent generation. By comparing with earlier report, the nobel‐metal (Ag) incorporated CuWO 4 showed the photocurrent 1.5 mA/cm 2 at 1.23 V vs NHE. In the present study, the Cu 2 O and CuO incorporated CuWO 4 showed high photocurrent 3.5 mA/cm 2 at 1.23 V vs RHE.…”

“…The first order derivative cut off wavelength is observed at 720 nm for particles. Its band gap value deduced using the formula (eV)=1240 /λ (nm) and found to be 1.78 eV (Figure S9), which is smaller than the reported of (2.1 ‐ 2.3 eV) ,…”

“…The heterostructured nanocomposite is a single material obtained by the integration of either two or more semiconductor nanomaterials . In order to prepare heterostructured nanocomposite, two or more‐steps needed for incorporation of another semiconductor as co‐catalyst on the surface of the bare photocatalyst or shell formation to cover the bare photocatalyst . In the heterostructure, interconnection between the photocatalyst and co‐catalyst plays a key role in the reduction of electron‐hole pair recombination.…”

“…Cu‐based ternary oxides (CuWO 4 , CuRhO 2 , CuRh 2 O 4 , CuNbO 3 , CuNb 2 O 6 and Cu 3 VO 4 ) are stable photocatalyst from neutral to basic condition of aqueous electrolyte . During the particle synthesis, island‐like nanosized or a thin layer of copper oxide (CuO) was inevictably produced on the surface of the ternary oxides.…”

Ag-Functionalized CuWO4/WO3 nanocomposites for solar water splitting

“…Please do not adjust margins Please do not adjust margins (3dx 2 -y 2 )) negatively affect the overall water splitting efficiency [13][14][15]18]. Generally, for tungstate-based semiconductors, various strategies have been reported to improve their usability [19][20][21][22][23][24][25][26][27][28][29].…”