The Catalytic Nanodiode: Detecting Continous Electron Flow at Oxide–Metal Interfaces Generated by a Gas‐Phase Exothermic Reaction

Abstract

Continuous flow of ballistic charge carriers is generated by an exothermic chemical reaction and detected using the catalytic metal-semiconductor Schottky diode. We obtained a hot electron current for several hours using two types of catalytic nanodiodes, Pt/TiO2 or Pt/GaN, during carbon monoxide oxidation at pressures of 100 Torr of O2 and 40 Torr of CO at 413-573 K. This result reveals that the chemical energy of an exothermic catalytic reaction is directly converted into hot electrons flux in the catalytic nanodiode. By heating the nanodiodes in He, we could measure the thermoelectric current which is in the opposite direction to the flow of the hot electron current. The chemicurrent is well correlated with the turnover rate of CO oxidation, which is separately measured with gas chromatography. The influence of the flow of hot charge carriers on the chemistry at the oxide-metal interface, and the turnover rate in the chemical reaction are discussed.

A review on plasmonic metal⿿TiO2 composite for generation, trapping, storing and dynamic vectorial transfer of photogenerated electrons across the Schottky junction in a photocatalytic system

“…Park and co-workers obtained a hot electron current using catalytic nanodiodes such as Pt/TiO 2 for CO oxidation [83]. This hot electron flow at the metal/oxide interface was found to be well connected with the turnover rates and selectivity of catalyzed reactions, since the local structure at the interface strongly affects the charge trapping, charge carrier dynamics, and the band structure [83].…”

“…This hot electron flow at the metal/oxide interface was found to be well connected with the turnover rates and selectivity of catalyzed reactions, since the local structure at the interface strongly affects the charge trapping, charge carrier dynamics, and the band structure [83]. There may be a limitation and an optimum arrangement in the design of metal/TiO 2 heterojunction to serve as highly active photocatalyst.…”

Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and Their Influence on Activity and Selectivity

“…Also, when vibrationally excited molecules strike another surface they are rapidly deexcited because of hot electron formation [42][43][44] . We fabricated a catalytic nanodiode where catalytically reactive platinum thin films were deposited on an oxide to form a Schottky barrier and we made contact to both sides of this barrier of Pt or Pd on TiO x or GaN [45][46][47] . Figure 18a shows the typical I-V curves measured on Pd/TiO x diode.…”

Concepts, instruments, and model systems that enabled the rapid evolution of surface science

“…As the surface becomes less positively charged, the acetonitrile orientation flips 180° with the CH 3 group pointing toward the surface. We constructed a so called catalytic nanodiode (59)(60)(61), which is composed of a metal of thickness less than the mean free path of hot electrons, deposited on a semiconductor surface, as shown in Figure 8a. When exothermic catalytic chemical reactions occur, we find that the heat transferred is converted to a hot electron flow that can pass through the metal film into the semiconductor which has a Schottky barrier (62; 63), which allows the passing of energetic electrons in one direction but not in the other direction.…”