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Interfacial Schottky barriers can impact the catalytic function of Pt on TiO2. Since the electronic structure is characteristic of each material, it may be advantageous to tailor the interfacial Schottky barrier by the addition of adsorbed layers. Here, we show that the Schottky barrier in Pt/TiO2can be mitigated by the insertion of self-assembled monolayers (SAM) of carboranethiols that possess an oriented dipole moment. A Pt substrate with the SAM on which TiO2nanoparticles are deposited is used to that effect. Kelvin Probe Force Microscopy shows thatm-9-carboranethiolate SAM with perpendicular dipole moments decreases the potential difference between TiO2and Pt by ∼0.3 eV due to the interfacial electric field of the SAM. Our findings open new opportunities for tailoring interfacial electronic structures not only in the metal-semiconductor junction, but also the semiconductor heterojunctions.

Nanoparticle aggregation of supported metal catalysts at high temperatures is a serious problem that causes a drop in catalytic performance. This study investigates the protection of metal nanoparticles from sintering by selectively forming nanoscale SiO 2 shells on Pd supported on TiO 2 by ultraviolet (UV) light irradiation. The proton-coupled reduction reaction increases the local pH around Pd nanoparticles, resulting in hydrolysis of tetraethoxyorthosilicate (TEOS) in only the vicinity of the metal. An apparent quantum efficiency of only 0.6% is obtained for the Pd/TiO 2 catalyst in H 2 evolution from ethanol-containing water under 370 nm excitation light. Therefore, the pH of raw slurry solution should be precisely controlled to that slightly below the threshold value for the TEOS hydrolysis reaction before the photodeposition. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) clearly show that the particle size of the Pd nanoparticles (∼40 nm) with the SiO 2 shell (∼20 nm) was almost unchanged by the high-temperature treatment at 900 °C in air, suggesting that the SiO 2 shell prevented thermal aggregation of Pd nanoparticles. The Pd/TiO 2 without SiO 2 shell decoration exhibited a drop in the number of active sites, which was likely due to aggregation of the Pd catalysts. However, the number of active sites on the Pd@SiO 2 /TiO 2 catalyst was maintained even after the catalyst was calcined at 900 °C. Consequently, the Pd@SiO 2 /TiO 2 catalyst maintained its catalytic performance for simulated exhaust gas purification even after treatment at 900 °C. This study presents a methodology to produce sintering-tolerant supported metal nanoparticles using the photocatalytic gas permeable layer fabrication method., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Concerns about energy and the environment are motivating a reexamination of catalytic processes, aiming to achieve more efficient and improved catalysis compatible with sustainability. Designing an active site for such heterogeneous catalytic processes remains a challenge leading to a next level breakthrough. Herein, we discuss a fundamental aspect of heterogeneous catalysis: the chemical potential of electrons in solid catalysts during thermal catalysis, which directly reflects the consequent catalytic reaction rate. The use of electrochemical tools during thermal catalysis allows for the quantitative determination of the ill-defined chemical potentials of solids in operando , whereby the potential-rate relationship can be established. Furthermore, the electrochemical means can also introduce the direct perturbation of catalyst potentials, in turn, perturbing the coverage of adsorbates functioning as poison, promoters, or reactants. We collect selected publications on these aspects, and provide a viewpoint bridging the fields of thermal- and electro-catalysis., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)