Goethite and Hematite Hybrid Nanosheet-Decorated YZnO NRs for Efficient Solar Water Splitting

Abstract

Hybrid metal-oxide nanostructures have drawn much attention recently because of their ability to overcome the disadvantages of each individual material to achieve high-performance solar water splitting. Using anodic electrochemical deposition, hybrid polycrystalline goethite (α-FeOOH) and hematite (α-Fe2O3) nanosheets (GOE/HM NSs) were successfully synthesized on yttrium-doped ZnO nanorods (YZO NRs). The unique morphology, with GOE/HM NSs wrapped around the length of vertically aligned YZO NRs, is favorable for light harvesting, charge transfer, and charge transportation. The density and the effective surface area of NSs were optimized for achieving a fine balance between light absorption and charge transportation between the photoanode and the electrolyte. The samples showed much improved water splitting efficiency under both UV and visible-light excitation, which represents the synergistic effects of GEO/HM NSs with YZO NRs. UV–vis absorption and incident photon-to-current conversion efficiency measurements demonstrated appropriate band alignment at interfaces, in addition to the reduced band gap energy. Electrochemical impedance spectroscopy measurements showed greatly reduced charge-transfer resistance. The hybrid material achieved an increase in the water splitting ability by a factor of 4.5 from pristine ZnO NRs (0.2 mA cm–2) to GOE/HM NSs-coated YZO NRs (0.92 mA cm–2). This represents a highly competitive strategy for improving the ability of ZnO for water splitting.

Extended Photoresponse in the UV–Visible Region with Multilayered Band Alignment in a In2S3-WO3-ZnO Nanostructure Heterojunction for Photoelectrochemical Water Splitting

“…The results show that the tetragonal phase for the In 2 S 3 sample has been formed with peak positions at 23.4, 27.4, 28.6, 33.3, 43.6, 50.2, and 66.7°, which are indexed to the diffraction planes (002), (113), (222), (004), (224), (044), and (226) . The XRD peaks for ZnO thin films at 30.67 and 51.74° correspond to the (001) and (102) planes for the wurtzite structure of ZnO . The WO 3 thin film shows peaks at 14.1, 22.9, 24.5, 28.3, 33.6, 36.8, 48.1, 50.9, and 55.5°, indexed to the (100), (002), (110), (111), (200), (202), (210), (212), (220), and (222), which are well matched and indexed to the pure hexagonal phase of WO 3 (JCPDS PDF-85-2459) .…”

Highly Polymerized Wine-Red Carbon Nitride to Enhance Photoelectrochemical Water Splitting Performance of Hematite

“…To evaluate the material’s PEC performance, WRCN was then loaded on hematite photoanode, establishing WRCN/hematite heterojunctions. The hematite photoanode was prepared on an FTO glass substrate through a hydrothermal method based on previous reports . The hematite has a porous nanorod morphology with diameters of tens of nanometers (Figure S11a).…”

“…The hematite photoanode was prepared on an FTO glass substrate through a hydrothermal method based on previous reports. 47 The hematite has a porous nanorod morphology with diameters of tens of nanometers (Figure S11a). However, WRCN nanosheets cannot be observed, possibly due to the close attachment of tiny WRCN nanosheets along the profiles of hematite nanorods.…”

Nanoscale ZnO/α‐Fe2O3 Heterostructures: Toward Efficient and Low‐Cost Photoanodes for Water Splitting

“…In a more recent research from the same group, the synthesis of hybrid polycrystalline goethite (α‐FeOOH) and hematite (α‐Fe 2 O 3 ) NSs (GOE/HM NSs) on yttrium‐doped ZnO NRs (YZO NRs) is proposed using anodic electrochemical deposition. [ 160 ] Proper engineering of the morphology is crucial in designing a promising system for PEC WS. In fact, GOE/HM NSs were wrapped around, rather than above, the YZnO NRs ( Figure ) and this unique setup was the key to get higher performances.…”