Unique Cd0.5Zn0.5S/WO3-x direct Z-scheme heterojunction with S, O vacancies and twinning superlattices for efficient photocatalytic water-splitting

Photocatalytic water-splitting employing the Z-scheme semiconductor systems mimicking natural photosynthesis is regarded as a promising way to achieve the efficient soalr-to-H2 conversion. Nevertheless, it still remains a big challenge to...

Remarkable Photocatalytic Behavior of WO3 /MoS2 Heterostructure: Insights From a Combined Experimental and Theoretical Investigations

The Z-scheme heterogeneous photocatalytic system simulates the natural photosynthesis process and can overcome the shortcomings of the single-component photocatalyst, and possess many merits, including increased light-harvesting, spatially separated reductive and oxidative sites, and well-preserved strong redox ability, which benefits the photocatalytic performance. Here we report the fabrication of a novel WO3/MoS2 heterojunction via the hydrothermal method, with the structure, electronic and photocatalytic properties analyzed by means of experimental and theoretical methods. Photocatalytic studies have been conducted on methylene blue dye under visible light in the presence of WO3/MoS2 heterostructure, and the degradation rate was as high as 90% within 60 min of light irradiation. A detailed theoretical study of this system shows that an internal electric field at the interface of the heterojunction was formed directed from MoS2 to WO3, which helps to separate the photogenerated electron-hole pairs efficiently through a direct Z-scheme charge transfer process. This work also demonstrated the significant potential of WO3/MoS2 heterostructure towards hydrogen evolution reaction.

A Bioinspired Strategy for Directional Charge Propagation in Photoelectrochemical Devices Using Supramolecular Machinery

Molecular photoelectrochemical (PEC) devices are hampered by electron–hole recombination after photoinduced electron transfer (PET), causing losses in power conversion efficiency (PCE). Inspired by natural photosynthesis, we demonstrate the use of molecular machinery as a strategy to inhibit recombination, through organization of molecular components and unbinding of the final electron acceptor after reduction. We show that preorganization of the macrocyclic 3-NDI-ring electron acceptor to the PSTATION dye forming the PSTATION:3-NDI-ring pseudorotaxane, enables a “ring launching” event, upon PET from PSTATION to 3-NDI-ring releasing 3-NDI-ring•−. Implementing PSTATION:3-NDI-ring into p-type dye-sensitized solar cells (p-DSSCs) revealed a fivefold increase in PCE compared to benchmark dye P1, unable to facilitate pseudorotaxane formation. This active repulsion of anionic 3-NDI-ring•− with concomitant reformation PSTATION:3-NDI-ring circumvents recombination at semiconductor–dye interface, affording a twofold enhancement in hole lifetime. We envision this concept of supramolecular-directed charge-propagation will encourage further integration of molecular machinery into PEC devices.

Boosting thermo-photocatalytic CO2 conversion activity by using photosynthesis-inspired electron-proton-transfer mediators

Natural photosynthesis proceeded by sequential water splitting and CO2 reduction reactions is an efficient strategy for CO2 conversion. Here, mimicking photosynthesis to boost CO2-to-CO conversion is achieved by using plasmonic Bi as an electron-proton-transfer mediator. Electroreduction of H2O with a Bi electrode simultaneously produces O2 and hydrogen-stored Bi (Bi-Hx). The obtained Bi-Hx is subsequently used to generate electron-proton pairs under light irradiation to reduce CO2 to CO; meanwhile, Bi-Hx recovers to Bi, completing the catalytic cycle. This two-step strategy avoids O2 separation and enables a CO production efficiency of 283.8 μmol g−1 h−1 without sacrificial reagents and cocatalysts, which is 9 times that on pristine Bi in H2 gas. Theoretical/experimental studies confirm that such excellent activity is attributed to the formed Bi-Hx intermediate that improves charge separation and reduces reaction barriers in CO2 reduction.

Integrating photon up- and down-conversion to produce efficient light-harvesting materials for enhancing natural photosynthesis

Using light-harvesting materials to enhance natural photosynthesis is attracting much attention in both materials and plant research. The working efficiency of most light-harvesting materials is, however, compromised by a narrow...

Enhanced the solar-to-hydrogen efficiency for photocatalytic water splitting based on polarized heterostructure: The role of intrinsic dipole in heterostructures

Inspired by natural photosynthesis, direct Z-scheme heterostructures are considered as promising photocatalysts for solar-driven water splitting and attract ever-growing interest. To date, it is still a challenge to achieve a...

Challenges and Prospects in the Selective Photoreduction of CO2 to C1 and C2 Products with Nanostructured Materials: A Review

Solar fuel generation through CO2 hydrogenation is the ultimate strategy to produce sustainable energy sources and alleviate global warming. The photocatalytic CO2 conversion process resembles natural photosynthesis, which regulates the...

Covalent grafting of molecular photosensitizer and catalyst on MOF-808: effect of pore confinement toward visible light-driven CO2 reduction in water

We have fabricated Zr-MBA-Ru/Re-MOFvia post-synthetic modification of MOF-808. The integrated catalyst assembly was used to mimic natural photosynthesis for sunlight-driven CO2 reduction to produce CO in aqueous medium without external sacrificial electron donor.