Hydrogen Oxidation-Mediated Current Discharge in Mesoporous Pt/TiO₂ Nanocomposite

Abstract

Here we report on direct evidence of a correlation between hydrogen-to-water oxidation on mesoporous Pt/TiO nanocomposites at room temperature and the conversion of surface-released chemical energy into a stationary electrical current. The Pt phase of this heterojunction device is an electrically continuous 15 nm thick mesh deposited onto a mesoporous TiO substrate fabricated with a plasma electrolytic oxidation process. The HO turnover frequency approaches an asymptotic value associated with the saturation of the Pt/TiO interface as the concentration of hydrogen gas is increased. In situ measurements of the reaction-induced current concurrently with mass spectrometry measurements illuminate the polarity switch of the reaction current (from thermionic emission to a reverse steady-state flow) simultaneously with the production of water. Furthermore, a concentration-dependent value of 5 min is measured as the time constant for the adsorption of the initial addition of H and HO formation and desorption.

Electronic Control of Hot Electron Transport Using Modified Schottky Barriers in Metal–Semiconductor Nanodiodes

“…Here, Park and Somorjai designed a Schottky nanodiode composed of metal–semiconductor for collecting hot electrons upon chemical reaction . Originating from the energy dissipation during the catalytic reaction, steady-state hot electron flow, termed “chemicurrent”, can be detected through an electrical circuit. − This chemicurrent study is highly associated with surface and interfaces at the nanoscale, which is dependent on the inherent properties of each material, like metal or semiconductors, and demonstrated by the differential trapping of electrons. , Recently, hot electron detection has been conducted for three-dimensional Schottky nanodiodes, demonstrating that hot electrons can be generated in practical metal–semiconductor catalysts based on nanotubular or mesoporous support oxide and can also be efficiently collected when an electrical circuit is established. − …”

Facile synthesis of Pt nanoparticles supported on anatase TiO2 nanotubes with good photo-electrocatalysis performance for methanol

“…It was reported that anodization of titanium metal foil to synthesis TiO 2 nanotubes is a simple way to obtain a high yield of products with vertical orientation arranged nanotube arrays. Nanostructured TiO 2 has great applicative potential in photoelectrochemical devices [46][47][48][49][50][51] due to the large effective lightharvesting interface area and wide band gap. As is known to all, the TiO 2 is a kind of excellent photoresponsive material.…”

A Voltage Bias Effect on Catalytic Activity of Electrically Continuous Pt/TiO2 Nanocomposites

“…TiO 2 films with a mesoporous morphology were grown on the parent metal titanium through a plasma electrolytic oxidation (PEO) process that has been reported elsewhere for these porous systems. [21][22][23][24][25] Research grade Ti metal with purity of 0.989 and dimensions of 36 × 12 × 0.5 mm 3 acted as the anode in an electrochemical cell, with a 153 × 26 × 6 mm 3 graphite cathode aligned parallel to the Ti, at a separation distance of 12 mm. Aqueous sulfuric acid (3M) was used as the electrolyte during galvanostatic oxidation of Ti with a current density of 93.2 mA•cm -2 .…”

“…The oxidation procedure was aborted abruptly after 20 min, resulting in a mesoporous TiO 2 layer of thickness 10 -11 µm. [21,24] A metal-semiconductor heterojunction was then fabricated by deposition of 0.9995 purity Pt onto the free TiO 2 surface through a 34 × 10 mm 2 mask via wide-angle physical vapor deposition at a constant rate of 0.02 nm•s -1 . This as-deposited Pt layer forms a mesh-like structure, with the Pt growth monitored by an Inficon quartz microbalance throughout the deposition process.…”