Well performing Fe-SnO2 for CO2 reduction to HCOOH

Multifunctional Roles of Clathrate Hydrate Nanoreactors for CO2 Reduction

In this study, we explore a possible platform for the CO2 reduction (CO2 R) in one of water's solid phases, namely clathrate hydrates (CHs), by ab initio molecular dynamics and well-tempered metadynamics simulations with periodic boundary conditions. We found that the stacked H2 O nanocages in CHs help to initialize CO2 R by increasing the electron-binding ability of CO2 . The substantial CO2 R processes are further influenced by the hydrogen bond networks in CHs. The first intermediate CO2 - in this process can be stabilized through cage structure reorganization into the H-bonded [CO2 - ⋅⋅⋅H-OHcage ] complex. Further cooperative structural dynamics enables the complex to convert into a vital transient [CO2 2- ⋅⋅⋅H-OHcage ] intermediate in a low-barrier disproportionation-like process. Such a highly reactive intermediate spontaneously triggers subsequent double proton transfer along its tethering H-bonds, finally converting it into HCOOH. These hydrogen-bonded nanoreactors feature multiple functions in facilitating CO2 R such as confining, tethering, H-bond catalyzing and proton pumping. Our findings have a general interest and extend the knowledge of CO2 R into porous aqueous systems.

Cutting-Edge Electrocatalysts for CO2RR

A world-wide growing concern relates to the rising levels of CO₂ in the atmosphere that leads to devastating consequences for our environment. In addition to reducing emissions, one alternative strategy is the conversion of CO₂ (via the CO₂ Reduction Reaction, or CO₂RR) into added-value chemicals, such as CO, HCOOH, C₂H₅OH, CH₄, and more. Although this strategy is currently not economically feasible due to the high stability of the CO₂ molecule, significant progress has been made to optimize this electrochemical conversion, especially in terms of finding a performing catalyst. In fact, many noble and non-noble metal-based systems have been investigated but achieving CO₂ conversion with high faradaic efficiency (FE), high selectivity towards specific products (e.g., hydrocarbons), and maintaining long-term stability is still challenging. The situation is also aggravated by a concomitant hydrogen production reaction (HER), together with the cost and/or scarcity of some catalysts. This review aims to present, among the most recent studies, some of the best-performing catalysts for CO₂RR. By discussing the reasons behind their performances, and relating them to their composition and structural features, some key qualities for an "optimal catalyst" can be defined, which, in turn, will help render the conversion of CO₂ a practical, as well as economically feasible process.

Highly Dispersed Few-Nanometer Chlorine-Doped SnO2 Catalyst Embedded in a Polyaniline Matrix for Stable HCOO- Production in a Flow Cell

With the spread of alternative energy plants, electrolysis processes are becoming the protagonists of the future industrial generation. The technology readiness level for the electrochemical reduction of carbon dioxide is still low and is largely based on precious metal resources. In the present work, tin ions are anchored on a polyaniline matrix, via a sonochemical synthesis, forming a few atomic layers of chlorine-doped SnO₂ with a total loading of tin atom load of only 7 wt %. This catalyst is able to produce formate (HCOO^-) with great selectivity, exceeding 72% of Faradaic efficiency in the first hour of testing in 1 M KHCO₃ electrolyte, with a current density of more than 50 mA cm^-2 in a 2 M KHCO₃ electrolyte flow cell setup. Catalyst stability tests show a stable production of HCOO^- during 6 h of measurement, accumulating an overall TON_HCOO^- of more than 10,000 after 16 h of continuous formate production. This strategy is competitive in drastically reducing the amount of metal required for the overall catalysis.