Mesoporous hematite photoanodes modified with a conductive water oxidation catalyst for photoelectrochemical water oxidation suffer from shunting which is alleviated via selective electrodeposition of the polymer PPO.

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Unraveling the charge-carrier dynamics at electrocatalyst/electrode interfaces is critical for the development of efficient photoelectrochemical (PEC) water oxidation. Unlike the majority of photoanodes investigated for PEC water oxidation, the integration of electrocatalysts with CuWO4 electrodes generally results in comparable or worse performance compared to the bare electrode. This is despite the fact that the surface state recombination limits the water oxidation efficiency with CuWO4 electrodes, and an electrocatalyst ought to bypass this reaction and improve performance. Here, we present results that deepen the understanding of the energetics and electron-transfer processes at the CuWO4/electrocatalyst interface, which controls the performance of such systems. Ni0.75Fe0.25O y (denoted as Ni75) was chosen as a model electrocatalyst, and through dual-working electrode experiments, we have been able to provide significant insight into the role of the electrocatalyst on the charge-transfer process at the CuWO4/Ni75 interface. We have shown a lack of performance improvement for CuWO4/Ni75 relative to the bare electrode to water oxidation. We attribute this surprising result to water oxidation on the CuWO4 surface kinetically outcompeting hole transfer to the Ni75 electrocatalyst interface.

In this paper, we present a simple platform for colorimetric detection of glutathione using gold nanorods (AR $ 6.5 AE 0.2) as a plasmonic sensor. The functional mechanism of the sensor is based on shifts of longitudinal plasmon resonance during selective transverse overgrowth induced by preferential binding of glutathione at the nanorod tips. Under the optimum conditions, a calibration curve showed two linear regimes at the range of 50 nM to 20 mM of glutathione with a detection limit as low as 40 nM. The nanosensor maintains relatively high selectivity for determination of glutathione in the presence of several other amino acids. However, cysteine at similar concentration levels strongly competes with glutathione for available binding sites, thereby interfering in the determination of glutathione. We employed multivariate curve resolution-alternating least square (MCR-ALS) to track the morphology variation of the nanorods and elucidate the kinetics of the overgrowth process in the presence of glutathione and cysteine.

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