Heteroatom Doping Restructures Interfacial H2O to Resolve Mechanistic Contradictions in CO2 Electroreduction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Interfacial water plays a crucial role in electrocatalysis.
• Controlling interfacial water structure is key to steering proton-coupled electron transfer (PCET) and selectivity.
• Developing methods to predictably program interfacial water is a significant challenge.

Purpose of the Study:

• To introduce nonmetal doping as a strategy to tune interfacial hydration on a tin dioxide (SnO2) catalyst.
• To investigate how different nonmetal dopants (N, P, S) affect interfacial water structure and PCET reactions.
• To establish a link between doping-defined hydration motifs and catalytic performance.

Main Methods:

• Nonmetal doping (N, P, S) of a model SnO2 catalyst.
• Characterization of interfacial water structure at the catalyst-electrolyte boundary.
• Electrocatalytic testing for PCET reactions, specifically formate formation.
• Analysis of reaction kinetics and selectivity in relation to interfacial structure.

Main Results:

• Sulfur (S) doping uniquely stabilizes a disordered, H-down hydration motif at the SnO2 interface.
• This S-induced hydration motif promotes water activation and directional proton delivery.
• PCET rates toward formate formation are accelerated by S doping, overriding weaker CO2 intermediate binding.
• A causal link between the doping-defined hydration motif and reaction kinetics was established.

Conclusions:

• Nonmetal doping is an effective materials-encoded strategy to program interfacial water structure.
• Interfacial water can be treated as a designable variable, not just a passive context, for optimizing electrocatalysis.
• This approach offers a broadly applicable method for enhancing PCET-governed transformations through interfacial solvation engineering.