Electrochemical Evaluation for Multiple Functions of Pt‐loaded TiO₂ Nanoparticles Deposited on a Photocathode

Abstract

Pt‐loaded TiO2 nanoparticles (Pt/TiO2) were deposited on a near‐infrared responsive photocathode as a reaction field for the photoelectrochemical (PEC) hydrogen evolution from water. The multiple functions of the Pt/TiO2 layer for improving the PEC performances were evaluated by electrochemical methods. Considering the electrochemically active surface area (ECSA) of Pt, the Pt/TiO2 surface modification was revealed to increase the number of active sites (Pt), resulting in a decreased current density per active site. Consequently, the potential of the Pt/TiO2‐modified photocathode surface during the PEC reaction was expected to be located around 38–46 mV vs. a reversible hydrogen electrode (mVRHE), while that of the unmodified one was negatively shifted to around 13 mVRHE. In addition, the TiO2 layer also functioned to block the migration of holes to the photocathode‐electrolyte interface due to its deep valence band position, as well as to improve the wettability of the photocathode surface during light irradiation. These combined effects of the TiO2, as a transparent and conductive support, enhanced the photocurrent, and stability of the photocathode.

A Three-Dimensional Branched TiO2 Photoanode with an Ultrathin Al2O3 Passivation Layer and a NiOOH Cocatalyst toward Photoelectrochemical Water Oxidation

“…The Nyquist The differences in electrochemically active surface areas (ECSAs) could be further estimated from the electrochemical double-layer capacitance (EDLC, C dl ) property with cyclic voltammetry (CV) measurements. 50,51 For accurate measurements of the ECSA of the as-obtained electrodes, no Faradaic current potential range of CV was selected. The CV curves of photoelectrodes obtained at the 0.5−0.6 V RHE region with different scan rates (20,40,60, and 80 mV s −1 ) are shown in Figure S5.…”

Modulating Charge Separation Efficiency of Water Oxidation Photoanodes with Polyelectrolyte‐Assembled Interfacial Dipole Layers

“…In principle, all types of semiconductors with a proper bandgap can absorb sunlight, generate excitons, and drive electrochemical reactions to produce valuable chemicals such as hydrogen and hydrocarbons . In this regard, various materials are being explored for efficient photogeneration of excitons and their catalytic applications, including Fe 2 O 3 , BiVO 4 , WO 3 , and TiO 2 as water oxidation photoanodes; Si and Cu 2 O as water reduction photocathodes; and cobalt phosphate and Pt nanoparticles as redox catalysts. However, most semiconductors retain inherent problems such as the short diffusion length of charge carriers, high recombination rate, and low charge separation efficiency .…”

Boosted Hydrogen‐Evolution Kinetics Over Particulate Lanthanum and Rhodium‐Doped Strontium Titanate Photocatalysts Modified with Phosphonate Groups

“…However, the propyl modification increased the contact angle to 89.6°. This hydrophilic surface would be expected to promote the detachment of evolved hydrogen gas [41] . The unique enhancement of the photocatalytic HER rate upon introducing the phosphonate groups, despite obtaining a similar degree of hydrophilicity compared to the other functional groups, indicates that the phosphonate groups modified the kinetics of the photocatalytic HER.…”