Efficient H₂ Production Using Ag₂S-Coupled ZnO@ZnS Core–Shell Nanorods Decorated Metal Wire Mesh as an Immobilized Hierarchical Photocatalyst

Abstract

Ag 2 S-coupled ZnO@ZnS core−shell nanorods heterostructures were grown on stainless steel wire mesh substrates along the c-axis by sulfidation of aligned ZnO nanorod arrays as immobilized hierarchical photocatalysts (Ag 2 S-coupled ZnO@ZnS/metal wire mesh) for photocatalytic H 2 production. The effects of the sulfidation time and AgNO 3 precursor concentration on the morphology, crystalline properties, optical property, photocurrent response, and photocatalytic H 2 production activity of the photocatalysts under UV or visible light irradiation, together with the stability of photocatalytic activity for recycled photocatalysts were investigated. In comparison with ZnO/metal wire mesh under the same conditions, the ZnO@ZnS/metal wire mesh photocatalysts showed excellent photocatalytic H 2 production activity that can be attributed to the formation of Ag 2 S-coupled ZnO−ZnS heterojunctions on conductive metal wire mesh substrate that favors the absorption of light, separation of photogenerated electron−hole pairs, and contact with the reactant solution. The H 2 production rates for Ag 2 S-coupled ZnO@ZnS/metal wire mesh photocatalysts reached 5870 and 168 μmol g −1 h −1 under UV and visible light irradiation.

Construction of 2D‐ZnS@ZnO Z‐Scheme Heterostructured Nanosheets with a Highly Ordered ZnO Core and Disordered ZnS Shell for Enhancing Photocatalytic Hydrogen Evolution

“…Finally, the generated charge carrier is further accelerated by the disorder ZnS shell, and the hydrogen produced in the CB of ZnS. The presence of hole scavenger of Na 2 S and Na 2 SO 3 accelerates the photocatalytic hydrogen evolution because the photogenerated holes can be scavenged by SO 3 2− and S 2− , and simultaneously hydrogen ions ionized from H 2 O can be reduced by photogenerated electrons and H 2 can be produced stably upon 2D‐ZnS@ZnO photocatalyst . The reactions can be expressed as following (Scheme ).…”

“…Therefore, it seems to be a Z‐scheme heterostructure rather than traditional II‐type heterostructure for ZnS@ZnO heterostructure in photocatalytic hydrogen production. Currently, one‐dimensional 1D‐ZnS@ZnO nanowires have been widely studied . At present, the 2D‐ZnS@ZnO through two step hydrothermal methods was rarely reported.…”

“…Currently, one-dimensional 1D-ZnS@ZnO nanowires have been widely studied. [20,21] At present, the 2D-ZnS@ZnO through two step hydrothermal methods was rarely reported. The 2D-ZnS@ZnO core-shell nanostructures is usually synthesized through annealing ZnS(en) 0.5 precursor at present.…”

A Review on the Fabrication of Hierarchical ZnO Nanostructures for Photocatalysis Application

“…For instance, sandwiched ZnO@Au@Cu2O nanorod films were synthesized on steel mesh substrates via a simple three-step approach and showed an efficient visible-light photocatalytic performance for the degradation of the MO solution [142]. Those non-doped ZnO hierarchical composites could also be used in the field of H2 generation [118,122,[143][144][145][146][147][148][149][150]. Barpuzary et al [143] prepared urchin-like CdS@ZnO hetero-arrays via a template-based method.…”

“…The heterostructure of CdS/Au/ZnO showed improved photocatalytic hydrogen evolution rate with 60.8 mmol h −1 , which was 4.5-times higher than the CdS/ZnO heterostructure. Furthermore, Hsu et al [146] reported that a hierarchical Ag2S-coupled ZnO@ZnS core−shell nanorod-decorated metal wire mesh showed higher H2 production rates reaching 5870 and 168 μmol g -1 h −1 under UV and visible light irradiation than ZnO/metal mesh. Thus, the fabrication of hierarchical ZnO-based heterostructures is a promising strategy to enhance both photocatalytic degradation and H2 generation.…”