Precise analyses of photoelectrochemical reactions on particulate ZnCdSe photoanodes in nonaqueous electrolytes using Ru bipyridyl complexes as a probe.

Recombination of photoexcited carriers at interface states is generally believed to strongly govern the photoelectrochemical (PEC) performance of semiconductors in electrolytes. Sacrificial reagents (, methanol or NaSO) are often used to assess the ideal PEC performance of photoanodes in cases of minimised interfacial recombination kinetics as well as accelerated surface reaction kinetics. However, varying the sacrificial reagents in the electrolyte means simultaneously changing the equilibrium potential and the number of electrons required to perform the sacrificial reaction, and thus the thermodynamic and kinetic aspects of the PEC reactions cannot be distinguished.

A Molecular Z-Scheme Artificial Photosynthetic System Under the Bias-Free Condition for CO Reduction Coupled with Two-electron Water Oxidation: Photocatalytic Production of CO/HCOOH and H O.

Bio-inspired molecular-engineered systems have been extensively investigated for the half-reactions of H O oxidation or CO reduction with sacrificial electron donors/acceptors. However, there has yet to be reported a device for dye-sensitized molecular photoanodes coupled with molecular photocathodes in an aqueous solution without the use of sacrificial reagents. Herein, we will report the integration of Sn - or Al -tetrapyridylporphyrin (SnTPyP or AlTPyP) decorated tin oxide particles (SnTPyP/SnO or AlTPyP/SnO ) photoanode with the dye-sensitized molecular photocathode on nickel oxide particles containing [Ru(diimine) ] as the light-harvesting unit and [Ru(diimine)(CO) Cl ] as the catalyst unit covalently connected and fixed within poly-pyrrole layer (RuCAT-RuC -PolyPyr-PRu/NiO).

Photocatalytic Systems for CO Reduction: Metal-Complex Photocatalysts and Their Hybrids with Photofunctional Solid Materials.

ConspectusPhotocatalytic CO reduction is a critical objective in the field of artificial photosynthesis because it can potentially make a total solution for global warming and shortage of energy and carbon resources. We have successfully developed various highly efficient, stable, and selective photocatalytic systems for CO reduction using transition metal complexes as both photosensitizers and catalysts. The molecular architectures for constructing selective and efficient photocatalytic systems for CO reduction are discussed herein.

Supramolecular photocatalysts fixed on the inside of the polypyrrole layer in dye sensitized molecular photocathodes: application to photocatalytic CO reduction coupled with water oxidation.

The development of systems for photocatalytic CO reduction with water as a reductant and solar light as an energy source is one of the most important milestones on the way to artificial photosynthesis. Although such reduction can be performed using dye-sensitized molecular photocathodes comprising metal complexes as redox photosensitizers and catalyst units fixed on a p-type semiconductor electrode, the performance of the corresponding photoelectrochemical cells remains low, , their highest incident photon-to-current conversion efficiency (IPCE) equals 1.2%.

Solar-Driven Photoelectrochemical Water Oxidation over an n-Type Lead-Titanium Oxyfluoride Anode.

Mixed-anion compounds (e.g., oxynitrides and oxysulfides) are potential candidates as photoanodes for visible-light water oxidation, but most of them suffer from oxidative degradation by photogenerated holes, leading to low stability.

Earth-Abundant Molecular Z-Scheme Photoelectrochemical Cell for Overall Water-Splitting.

A push-pull organic dye and a cobaloxime catalyst were successfully cografted on NiO and CuGaO to form efficient molecular photocathodes for H production with >80% Faradaic efficiency. CuGaO is emerging as a more effective p-type semiconductor in photoelectrochemical cells and yields a photocathode with 4-fold higher photocurrent densities and 400 mV more positive onset photocurrent potential compared to the one based on NiO. Such an optimized CuGaO photocathode was combined with a TaON|CoO photoanode in a photoelectrochemical cell.

Electrocatalytic reduction of low concentration CO.

Utilization of low concentration CO contained in the exhaust gases from various industries and thermal power stations without the need for energy-consuming concentration processes should be an important technology for solving global warming and the shortage of fossil resources. Here we report the direct electrocatalytic reduction of low concentration CO by a Re(i)-complex catalyst that possesses CO-capturing ability in the presence of triethanolamine. The reaction rate and faradaic efficiency of CO reduction were almost the same when using Ar gas containing 10% CO or when using pure CO gas, and the selectivity of CO formation was very high (98% at 10% CO).

Photoelectrochemical CO Reduction Using a Ru(II)-Re(I) Supramolecular Photocatalyst Connected to a Vinyl Polymer on a NiO Electrode.

A Ru(II)-Re(I) supramolecular photocatalyst and a Ru(II) redox photosensitizer were both deposited successfully on a NiO electrode by using methyl phosphonic acid anchoring groups and the electrochemical polymerization of the ligand vinyl groups of the complexes. This new molecular photocathode, poly-RuRe/NiO, adsorbed a larger amount of the metal complexes compared to one using only methyl phosphonic acid anchor groups, and the stability of the complexes on the NiO electrode were much improved. The poly-RuRe/NiO acted as a photocathode for the photocatalytic reduction of CO at E = -0.

Hybrid photocathode consisting of a CuGaO p-type semiconductor and a Ru(ii)-Re(i) supramolecular photocatalyst: non-biased visible-light-driven CO reduction with water oxidation.

A CuGaO p-type semiconductor electrode was successfully employed for constructing a new hybrid photocathode with a Ru(ii)-Re(i) supramolecular photocatalyst (/CuGaO). The /CuGaO photocathode displayed photoelectrochemical activity for the conversion of CO to CO in an aqueous electrolyte solution with a positive onset potential of +0.3 V Ag/AgCl, which is 0.

Photoelectrochemical Reduction of CO Coupled to Water Oxidation Using a Photocathode with a Ru(II)-Re(I) Complex Photocatalyst and a CoO/TaON Photoanode.

Photoelectrochemical CO reduction activity of a hybrid photocathode, based on a Ru(II)-Re(I) supramolecular metal complex photocatalyst immobilized on a NiO electrode (NiO-RuRe), was confirmed in an aqueous electrolyte solution. Under half-reaction conditions, the NiO-RuRe photocathode generated CO with high selectivity, and its turnover number for CO formation reached 32 based on the amount of immobilized RuRe. A photoelectrochemical cell comprising a NiO-RuRe photocathode and a CoO/TaON photoanode showed activity for visible-light-driven CO reduction using water as a reductant to generate CO and O, with the assistance of an external electrical (0.

A Z-scheme photocatalyst constructed with an yttrium-tantalum oxynitride and a binuclear Ru(ii) complex for visible-light CO2 reduction.

An yttrium-tantalum oxynitride having a band gap of 2.1 eV (absorbing visible light at <580 nm) was applicable as a semiconductor component of a Z-scheme CO2 reduction system operable under visible light, in combination with a binuclear Ru(ii) complex that has strong absorption in the visible region (<600 nm). Excitation of this system with visible light under a CO2 atmosphere induced photocatalytic formation of formic acid with very high selectivity (>99%).

A Photoelectrochemical Solar Cell Consisting of a Cadmium Sulfide Photoanode and a Ruthenium-2,2'-Bipyridine Redox Shuttle in a Non-aqueous Electrolyte.

A photoelectrochemical (PEC) cell consisting of an n-type CdS single-crystal electrode and a Pt counter electrode with the ruthenium-2,2'-bipyridine complex [Ru(bpy)3](2+/3+) as the redox shuttle in a non-aqueous electrolyte was studied to obtain a higher open-circuit voltage (V(OC)) than the onset voltage for water splitting. A V(OC) of 1.48 V and a short-circuit current (I(SC)) of 3.

Stable hydrogen evolution from CdS-modified CuGaSe2 photoelectrode under visible-light irradiation.

The photoelectrochemical properties of CuGaSe2 modified by deposition of a thin CdS layer were investigated. The CdS layer formed a p-n junction on the surface of the electrode, improving its photoelectrochemical properties. There was an optimal CdS thickness because of the balance between the charge separation effect and light absorption by CdS.