Temperature-dependent electrochemical CO2-to-CO conversion on the bimetallic Ti–Ag nanocluster

Abstract

The electrochemical CO₂ reduction reaction (CO₂RR) to carbon monoxide (CO) represents a promising route for sustainable fuel production and carbon neutrality. While bimetallic catalysts often exhibit superior performance, the fundamental understanding of how their structure governs activity and selectivity, particularly under varying reaction temperatures, remains limited. Herein, we report an atomically precise titanium–silver bimetallic nanocluster catalyst (Ti₅Ag) as an ideal model system to unravel the temperature-dependent behavior in CO₂RR. This catalyst achieves a maximum CO faradaic efficiency (FE_CO) of ∼60% and a yield rate of ∼64 mmol g⁻¹ h⁻¹. A strong temperature-dependent catalytic performance was discovered: elevated reaction temperature (55 °C) dramatically enhances activity by reducing interfacial resistances by 1–2 orders of magnitude. In contrast, lowered temperature (−1 °C) favors superior CO selectivity by suppressing the competing hydrogen evolution reaction (HER) more effectively. Mechanistic studies identify the surface reduction of COOH* to CO* as the rate-determining step (RDS) with a Tafel slope of 50–56 mV dec⁻¹. This study transcends the conventional catalyst screening by providing deep mechanistic insights into reaction dynamics, offering a new design principle for efficient CO₂ conversion catalysts through the manipulation of operational temperature.