Kanazawa University NanoLSI Podcast:Enhancing carbon dioxide reduction

Kanazawa University NanoLSI Podcast: Enhancing carbon dioxide reduction

Transcript of this podcast

Hello and welcome to the NanoLSI podcast. Thank you for joining us today. In this episode we feature the latest research by Yasafumi Takahashi at the Kanazawa University NanoLSI and Yoshikazu Ito and Yuta Hori at the University of Tsukuba.

The research described in this podcast was published in ACS Nano in June 2023

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Enhancing carbon dioxide reduction

Researchers at Kanazawa University report in ACS Nano how ultrathin layers of tin disulfide can be used to accelerate the chemical reduction of carbon dioxide — a finding that is highly relevant for our quest towards a carbon-neutral society.

Recycling carbon dioxide released by industrial processes is a must in humanity’s urgent quest for a sustainable, carbon-neutral society.  For this purpose, electrocatalysts that can efficiently convert carbon dioxide into other, less impactful chemical products are widely researched today.  A category of materials known as two-dimensional (2D) metal dichalcogenides are candidate electrocatalysts for carbon dioxide conversion, but these materials also typically facilitate competing reactions, which compromises their efficiency.  Yasufumi Takahashi from Nano Life Science Institute (WPI-NanoLSI), at Kanazawa University and colleagues have now identified a 2D metal dichalcogenide that can efficiently reduce carbon dioxide to formic acid, a compound that not only occurs naturally but is also an intermediate product in chemical synthesis.

Takahashi and colleagues compared the catalytic performance of 2D sheets of molybdenum disulfide and tin disulfide.  Both are 2D metal dichalcogenides, with the latter of particular interest because pure tin is a known catalyst for the production of formic acid.  Electrochemical tests of these compounds revealed that with molybdenum disulfide, instead of carbon dioxide conversion, hydrogen evolution reactions were promoted.  Hydrogen evolution reactions refer to reactions yielding hydrogen, which can be useful when the production of hydrogen gas fuel is intended, but in the context of carbon dioxide reduction it is an unwanted competing process.  Tin disulphide, on the other hand, showed good carbon dioxide reduction activity and suppressed hydrogen evolution reactions.  The researchers also carried out electrochemical measurements for bulk tin dioxide powder, which was found to have less catalytic carbon dioxide reduction activity.

So how is tin disulphide facilitating carbon dioxide reduction?

To understand where the catalytically active sites are in tin disulphide, and why the 2D material performs better than the bulk compound, the scientists applied a method called scanning electrochemical cell microscopy (SECCM).  SECCM is used as a nanopipette to form the meniscus shape nanoscale electrochemical cell for the surface reactivity sensing probe on the sample.  The measurements revealed that the whole surface of the tin disulphide sheet is catalytically active, not only ‘terrace’ or ‘edge’ features in the structure.  This also explains why 2D tin disulphide has enhanced activity compared to bulk tin disulphide.

Calculations provided further insights into the chemical reactions at play.  Specifically, the formation of formic acid was confirmed as an energetically favorable reaction pathway when using 2D tin disulphide as catalyst.

The results of Takahashi and colleagues signify an important step forward towards the use of 2D electrocatalysts in electrochemical carbon dioxide reduction applications.  Quoting the scientists: “These findings will provide a better understanding and desig

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