Facile Fabrication of Sandwich Structured WO₃ Nanoplate Arrays for Efficient Photoelectrochemical Water Splitting

Abstract

Herein, sandwich structured tungsten trioxide (WO3) nanoplate arrays were first synthesized for photoelectrochemical (PEC) water splitting via a facile hydrothermal method followed by an annealing treatment. It was demonstrated that the annealing temperature played an important role in determining the morphology and crystal phase of the WO3 film. Only when the hydrothermally prepared precursor was annealed at 500 °C could the sandwich structured WO3 nanoplates be achieved, probably due to the crystalline phase transition and increased thermal stress during the annealing process. The sandwich structured WO3 photoanode exhibited a photocurrent density of 1.88 mA cm(-2) and an incident photon-to-current conversion efficiency (IPCE) as high as 65% at 400 nm in neutral Na2SO4 solution under AM 1.5G illumination. To our knowledge, this value is one of the best PEC performances for WO3 photoanodes. Meanwhile, simultaneous hydrogen and oxygen evolution was demonstrated for the PEC water splitting. It was concluded that the high PEC performance should be attributed to the large electrochemically active surface area and active monoclinic phase. The present study can provide guidance to develop highly efficient nanostructured photoelectrodes with the favorable morphology.

Low field magneto-tunable photocurrent in CoFe2O4 nanostructure films for enhanced photoelectrochemical properties

“…The semi arc curves are simulated using an equivalent circuit model (shown in the inset of Fig. 4b) with Z-View software and matched with experimental observations 42,43 . The solid lines are the simulted curves.…”

Protected Hematite Nanorod Arrays with Molecular Complex Co‐Catalyst for Efficient and Stable Photoelectrochemical Water Oxidation

“…To further investigate the PEC performance of the obtained photoanodes, the electrochemically active surface area (ECSA) was measured according to the equation (1): where C dl represents the electrochemical double‐layer capacitance of the electrode surface, C s is the intrinsic specific capacitance. Assuming the same C s for all the photoanodes, the ECSA could be determined by the C dl , . With C dl calculated from the slope of current densities as a function of the scan rates in the cyclic voltammetry (CV) curves (Figure S9), it is observable that the C dl of α‐Fe 2 O 3 /Co(dca) 2 (53 µF cm –2 ) is very close to that of α‐Fe 2 O 3 (47 µF cm –2 ), while α‐Fe 2 O 3 /Co(dca) 2 /TiO 2 shows C dl greatly increased up to 74 µF cm –2 (Figure d).…”

“…Assuming the same C s for all the photoanodes, the ECSA could be determined by the C dl . [52,53] With C dl calculated from the slope of current densities as a function of the scan rates [54] in the cyclic voltammetry (CV) curves ( Figure S9), it is observable that the C dl of α-Fe 2 O 3 /Co(dca) 2 (53 μF cm -2 ) is very close to that of α-Fe 2 O 3 (47 μF cm -2 ), while α-Fe 2 O 3 /Co(dca) 2 /TiO 2 shows C dl greatly increased up to 74 μF cm -2 (Figure 3d). These results mean that the Co(dca) 2 molecular complex as WOC would bring negligible change to the ECSA of the photoanodes while the TiO 2 overlayer could effectively enhance the ECSA.…”

SnS2 Nanosheets/H‐TiO2 Nanotube Arrays as a Type II Heterojunctioned Photoanode for Photoelectrochemical Water Splitting

“…[4] Various type II heterostructures such as BiVO 4 /TiO 2 , [5] CdS/TiO 2 , [6] ZnS/ZnO, [7] or Fe 2 O 3 /Fe 2 TiO 5 , [8] have been designed to improve electron-hole separation efficiency.Normally,the type of band alignment between two materials is relatively set owing to their relativelyf ixed valenceand conduction-band positions if those two materials are chosen. [16] Therefore, this structure has been widely demonstrated for WO 3 , [17] BiOX (X = Cl, Br,I ), [18] Fe 2 O 3 , [19] and In 2 S 3 [20] in PEC applications.2 Dg raphene-like layered SnS 2 crystals, possessing av isible-light band gap of 2.2-2.35eVa nd ap eculiar CdI 2 -type layered structure [a] J. For example, the transition from type It ot ype II band alignment can greatly improve the performance and therefore broaden the application range of photoelectrochemical( PEC) materials.…”

“…[9] TiO 2 nanotubes (NTs) have attracted wide interesti nm any photocatalytic and photoelectrochemical reactions, for example, to facilitate carrier separation by the NTs. [16] Therefore, this structure has been widely demonstrated for WO 3 , [17] BiOX (X = Cl, Br,I ), [18] Fe 2 O 3 , [19] and In 2 S 3 [20] in PEC applications.2 Dg raphene-like layered SnS 2 crystals, possessing av isible-light band gap of 2.2-2.35eVa nd ap eculiar CdI 2 -type layered structure consistingo fS -Sn-S triple layers, [21] have been applied in photocatalytic CO 2 reduction [22] and PEC water splitting. [10] This is particularly beneficial to break the limitations resulting from the short diffusion length of holes in TiO 2 ( % 10 nm) and simultaneously exploiting the long electron diffusion length ( % 20 mmi nT iO 2 NTs).…”