Visible Light-Driven Photoelectrocatalytic Water Splitting Using Z-Scheme Ag-Decorated MoS₂/RGO/NiWO₄ Heterostructure

Abstract

Herein, we have successfully constructed a solid-state Z-scheme photosystem with enhanced light absorption capacity by combining the optoelectrical properties of AgNPs with those of the MoS 2 /RGO/NiWO 4 (Ag-MRGON) heterostructure. The Ag-MRGON Zscheme system demonstrates improved photo-electrochemical (PEC) water-splitting performance in terms of applied bias photon-to-current conversion efficiency (ABPE), which is 0.52%, and 17.3-and 4.3-times better than those of pristine MoS 2 and MoS 2 /NiWO 4 photoanodes, respectively. The application of AgNPs as an optical property enhancer and RGO as an electron mediator improved the photocurrent density of Ag-MRGON to 3.5 mA/cm 2 and suppressed the charge recombination to attain the photostability of ∼2 h. Moreover, the photocurrent onset potential of the Ag-MRGON heterojunction (i.e., 0.61 V RHE ) is cathodically shifted compared to those of NiWO 4 (0.83 V RHE ), MoS 2 (0.80 V RHE ), and MoS 2 /NiWO 4 heterojunction (0.73 V RHE ). The improved PEC water-splitting performance in terms of ABPE, photocurrent density, and onset potential is attributed to the facilitated charge transfer through the RGO mediator, the plasmonic effect of AgNPs, and the proper energy band alignments with the thermodynamic potentials of hydrogen and oxygen evolution.

Versatile Bifunctional Ag@g-C3N4/r-GO Catalyst for Efficient Photo- and Electrocatalytic H2 Production

“…It is worth mentioning that photogenerated electrons transported from g-C 3 N 4 and originally excited electrons on Ag particles are impacted by surface plasma resonance. Ag particles have a limited capacity for catalytic hydrogen creation, as previously mentioned; therefore, SPR supplied to H + is not sufficient in the absence of e – from g-C 3 N 4 . − …”

“…As a result of its excellent thermal and chemical stability as well as its appropriate band energy, g-C 3 N 4 is an appealing material for photocatalysis. − The electronic conductivity, surface area, and remarkable adsorption capabilities of g-C 3 N 4 are all enhanced by the addition of carbon nanomaterials, like r-GO. Combining g-C 3 N 4 with r-GO enhanced the visible-light responsiveness, lengthened the lifetime of the photogenerated charge carriers, enhanced the adsorption properties, and raised the specific surface area. − The employment of physical and chemical interactions to integrate different building blocks in the development of these heterostructured photocatalysts is a particularly versatile approach. − All of these heterostructures now have new opportunities for scientific study and technological use in photocatalysis, owing to the newly developed 2D/2D or three-dimensional (3D)/2D heterojunctions, which have exceptional qualities, such as their clear “face to face” connection with a great interface space and solid interactions, the wide range of light responsiveness enclosed by many 2D materials with varying bandwidth, the improved interfacial charge separation, and other factors. − …”

2D material based heterostructures for solar light driven photocatalytic H2production

“…A solid-state Ag NP-decorated MoS 2 /reduced graphene oxide (RGO)/NiWO 4 Z-scheme photosystem was constructed. 179 In addition to the Z-scheme function, the RGO mediator and the plasmonic effect of Ag NPs facilitate the charge transfer to enhance photocatalytic efficiency. Nagajyothi et al 180 reported a ZnFe 2 O 4 / MoS 2 Z-scheme heterostructure achieved an H 2 production rate of 142.1 mmol h À1 g À1 , which is 2.3 times higher than that of pristine MoS 2 .…”

New trends on photoelectrocatalysis (PEC): nanomaterials, wastewater treatment and hydrogen generation

“…The improvement of photoelectrodes is of course important to enhance the overall performance. Lower band gap materials and/or heterostructures may offer improved solar performance by utilising more visible light, with extensive investigations primarily focused on solar energy harvesting rather than water treatment [11].…”