Particulate metal chalcogenides for photocatalytic Z-scheme overall water splitting

Advances in the structural engineering of layered bismuth-based semiconductors for visible light-driven photocatalytic water splitting

“…Such configuration consisting of two separate light absorbers in responsible for water oxidation and proton reduction reactions, respectively, is conducive to achieving both the high-efficiency separation of photogenerated charges and ensuring a substantial redox driving force, thus mitigating the challenges associated with kinetic overpotentials. 10…”

Synthesis of Highly Active GaN:ZnO Photocatalysts Applicable to Z-Scheme Overall Water Splitting Systems

“…The fundamental constituents of a Z-scheme OWS system encompass a hydrogen evolution photocatalyst (HEP) and an oxygen evolution photocatalyst (OEP). Since the photoexcited holes on HEP and electrons on OEP must be neutralized to complete the entire charge circulation, three primary types of Z-scheme systems are designed: (i) deposition of HEP and OEP on a conductive sheet following the concept of p–n conjugated photoelectrochemical (PEC) reaction, (ii) direct physical collision between HEP and OEP particles suspended randomly in water, and (iii) suspension of HEP and OEP particles in an aqueous solution containing ionic redox pairs as electron mediators. ,, It is noted that each type of Z-scheme has its specific challenges for the selection of HEP and OEP materials. The oxygen evolution reaction (OER) during water oxidation is a four-electron process with complex kinetics and a high overpotential, which has generally been identified as the rate-limiting step in Z-scheme OWS .…”

Recent Advances in Redox-Based Z-Scheme Overall Water Splitting under Visible Light Irradiation

“…Through combining two different narrow bandgap semiconductors, H 2 -evolving photocatalyst (HEP) and O 2 -evolving photocatalyst (OEP) and coupling with electron mediator to realize the electron cycle, the Z-scheme photocatalytic OWS is achieved . The electron mediator in this system can be aqueous redox couples such as IO 3 – /I – , Fe 3+/2+ , [Fe­(CN) 6 ] 4–/3– , solid-state electron mediator (Au, Ir, reduced graphene oxide, and carbon dots), or physical contact to realize the interparticle electron transfer between the HEP and OEP. − In addition, there is another special type called direct Z-scheme heterojunction, relying on direct interface intimate contact to recombine the electrons from the OEP and holes from the HEP. , One advantage of the Z-scheme OWS system is lowering the energy required for photocatalysis, making full use of visible light possible. In other words, a semiconductor owning only a water oxidation or proton reduction potential suitable for one side can also be applied.…”