Country for PR: Japan
Contributor: Kyodo News JBN
Wednesday, March 16 2022 - 19:00
Selective Hybrid Photocatalyst Allows Oxidative Coupling of Methane to Ethane with Dioxygen: WPI-MANA
TSUKUBA, Japan, Mar. 16, 2022 /Kyodo JBN-AsiaNet/ --

A team at the International Center for Materials Nanoarchitectonics (WPI-MANA) 
has demonstrated that methane can be efficiently and selectively oxidized to 
ethane with oxygen under light irradiation over an Au-ZnO/TiO2 hybrid. This 
achievement opens the door to cheaper and more efficient production of valuable 
chemicals using methane as a feedstock.


Methane (CH4), the main component of natural gas and shale gas, is not only an 
abundant and low-cost fuel, but also a powerful greenhouse gas with a potential 
28-34 times that of CO2. Directly and selectively converting methane to 
value-added higher hydrocarbons or oxygenates has been attracting substantial 
interest from both academia and industry, and could reduce society's reliance 
on crude oil and contribute to carbon neutrality.

However, the high C-H bond dissociation energy and non-polar nature of methane, 
along with the higher reactivity of the desired products, make selective 
activation and conversion of methane challenging.

The WPI-MANA group designed an Au-ZnO/TiO2 hybrid photocatalyst for selectively 
oxidizing CH4 to ethane (C2H6) with oxygen (O2). This showed a high C2H6 
production rate with high selectivity and excellent durability, which were more 
than one order of magnitude higher than the state-of-the-art photocatalytic 

Mechanistic studies showed that the formation of ZnO/TiO2 heterojunctions by 
precisely controlling the ratio and interface structure of ZnO/TiO2 led to 
enhanced activity, while maintaining high selectivity owing to the weak 
overoxidation ability of the main component ZnO. Moreover, using Au 
nanoparticles as the cocatalyst not only promotes charge separation, but also 
facilitates methyl (CH3) species desorption to form methyl radicals, which 
promotes the formation of C2H6 and inhibits the overoxidation of CH4 to CO2.

These findings could guide the future design of photocatalysts that could 
transform methane to ethane with high activity and selectivity. This, along 
with other technologies such as new reactor designs, could provide an 
economically viable way to directly convert methane into ethane. 

This research was conducted by Jinhua Ye (MANA Principal Investigator, Group 
Leader, Photocatalytic Materials Group, WPI-MANA, NIMS) and her collaborators.

Research Highlights Vol. 76


Source: International Center for Materials Nanoarchitectonics (WPI-MANA), 
National Institute for Materials Science (NIMS)