CuWO₄ Nanoflake Array-Based Single-Junction and Heterojunction Photoanodes for Photoelectrochemical Water Oxidation

Abstract

Over recent years, tremendous efforts have been invested in the search and development of active and durable semiconductor materials for photoelectrochemical (PEC) water splitting, particularly for photoanodes operating under a highly oxidizing environment. CuWO4 is an emerging candidate with suitable band gap and high chemical stability. Nevertheless, its overall solar-to-electricity remains low because of the inefficient charge separation process. In this work, we demonstrate that this problem can be partly alleviated through designing three-dimensional hierarchical nanostructures. CuWO4 nanoflake arrays on conducting glass are prepared from the chemical conversion of WO3 templates. Resulting electrode materials possess large surface areas, abundant porosity and small thickness. Under illumination, our CuWO4 nanoflake array photoanodes exhibit an anodic current density of ∼0.4 mA/cm(2) at the thermodynamic potential of water splitting in pH 9.5 potassium borate buffer--the largest value among all available CuWO4-based photoanodes. In addition, we demonstrate that their performance can be further boosted to >2 mA/cm(2) by coupling with a solution-cast BiVO4 film in a heterojunction configuration. Our study unveils the great potential of nanostructured CuWO4 as the photoanode material for PEC water oxidation.

Unraveling the Photocatalytic Water Dissociation Pathways on Two‐Dimensional Conjugated Polymers

“…Converting solar energy into storable chemical fuels via photocatalytic water splitting is a potentially viable route toward producing clean and sustainable energy in the future . In particular, photocatalytic overall water splitting, which can decompose pure H 2 O into stoichiometric amounts of H 2 and O 2 without using any sacrificial agents, is fundamentally important but still remains challenging .…”

Significant Enhancement of the Photoelectrochemical Activity of CuWO4 by using a Cobalt Phosphate Nanoscale Thin Film

“…Semiconductors such as TiO 2 , BiVO 4 , WO 3 , and Fe 2 O 3 are the most widely studied metal oxides for PEC water splitting. [5,7,[12][13][14][15][16][17][18][19][20][21][22][23] Very recently, another n-type semiconductor, copper tungstate (CuWO 4 ), has generated great research interest as a robust and inexpensive photocatalyst, [24][25][26][27][28][29][30] as it has an ideal bandgap (Eg) of approximately 2.2 eV and a large visible light absorption range. Its conduction band level is slightly more positive than the proton reduction potential of 0.0 V vs NHE, while its valence band level is thermodynamically suitable for oxygen evolution of 1.23 V vs NHE.…”

Efficient Photoelectrocatalytic Activity of CuWO4 Nanoplates towards the Oxidation of NADH Driven in Visible Light

“…The TEM analysis provides more detailed structural information of the nano‐sized plates like CuWO 4 [Figure S3 (A−C)]. The high resolution TEM image shows that the lattice fringe width of 0.476 nm which corresponds to the (100) plane of CuWO 4 . Figure S4 shows the XRD pattern of CuWO 4 nanoplates.…”

“…The high resolution TEM image shows that the lattice fringe width of 0.476 nm which corresponds to the (100) plane of CuWO 4 . [28] Figure S4 shows the XRD pattern of CuWO 4 nanoplates. It clearly shows the pure phase of CuWO 4 (JCPDS NO_88-0269) without the other impurities like tungstic oxide or copper oxide.…”