Embedding biocatalysts in a redox polymer enhances the performance of dye-sensitized photocathodes in bias-free photoelectrochemical water splitting

Dye-sensitized photoelectrodes consisting of photosensitizers and molecular catalysts with tunable structures and adjustable energy levels are attractive for low-cost and eco-friendly solar-assisted synthesis of energy rich products. Despite these advantages, dye-sensitized NiO photocathodes suffer from severe electron-hole recombination and facile molecule detachment, limiting photocurrent and stability in photoelectrochemical water-splitting devices. In this work, we develop an efficient and robust biohybrid dye-sensitized NiO photocathode, in which the intermolecular charge transfer is enhanced by a redox polymer. Owing to efficient assisted electron transfer from the dye to the catalyst, the biohybrid NiO photocathode showed a satisfactory photocurrent of 141±17 μA·cm-2 at neutral pH at 0 V versus reversible hydrogen electrode and a stable continuous output within 5 h. This photocathode is capable of driving overall water splitting in combination with a bismuth vanadate photoanode, showing distinguished solar-to-hydrogen efficiency among all reported water-splitting devices based on dye-sensitized photocathodes. These findings demonstrate the opportunity of building green biohybrid systems for artificial synthesis of solar fuels.

Solid state p-type dye sensitized NiO-dye-TiO2 core-shell solar cells

Solid state p-type dye sensitized NiO-dye-TiO2 core-shell solar cells with an organic dye PB6 were successfully fabricated for the first time. With Al2O3 as an inner barrier layer, the recombination process between injected holes in NiO and injected electrons in TiO2 was significantly suppressed and the charge transport time was also improved.

Ultrafast dye regeneration in a core-shell NiO-dye-TiO2 mesoporous film

In this study, a core-shell NiO-dye-TiO₂ mesoporous film was fabricated for the first time, utilizing atomic layer deposition technique and a newly designed triphenylamine dye. The structure of the film was confirmed by SEM, TEM, and EDX. Excitation of the dye led to efficient and fast charge separation, by hole injection into NiO, followed by an unprecedentedly fast dye regeneration (t_1/2 ≤ 500 fs) by electron transfer to TiO₂. The resulting charge separated state showed a pronounced transient absorption spectrum caused by the Stark effect, and no significant decay was found within 1.9 ns. This indicates that charge recombination between NiO and TiO₂ is much slower than that between the NiO and the reduced dye in the absence of the TiO₂ layer (t_1/2 ≈ 100 ps).

Correction: Ultrafast dye regeneration in a core–shell NiO–dye–TiO2 mesoporous film

Correction for ‘Ultrafast dye regeneration in a core–shell NiO–dye–TiO₂ mesoporous film’ by Lei Tian et al., Phys. Chem. Chem. Phys., 2018, 20, 36–40.

Nanoscale colour control: W-O graded coatings deposited by magnetron sputtering

A new design of decorative tungsten oxide coatings is presented. The coatings were deposited with a graded refractive index by magnetron sputtering from a tungsten target and pulsing the reactive gas. The controlled injection of the reactive gas can produce a concentration profile gradient from pure tungsten to tungsten trioxide, determining the final apparent colour of the coating. A dynamic sputtering model was built to simulate the growth of the coating during the reactive gas pulsing which was validated by direct measurement of the gradient of the oxygen content in the deposited coatings. Finally, these results were used for an optical model allowing the optical properties of the deposited tungsten oxide layer to be described, again validated by experimental analysis. This procedure allows the deposition of coatings with the desired colour by using the models to finding the optimal oxygen pulse parameters. This proposed method can be easily applied to almost any metal/metal oxide system.