Catalytic conversion of CO₂ to value-added chemicals represents a pathway for mitigating CO₂ emissions. Many recent studies have demonstrated promising results of CO₂ conversion by either thermocatalysis or electrocatalysis. In this article, we discuss tandem electrocatalytic-thermocatalytic processes that potentially have advantages over either process alone. We use the conversion of CO₂ to propanal/propanol as a case study to illustrate the feasibility of the tandem process. We also discuss opportunities and challenges for converting CO₂ using tandem electrocatalytic-thermocatalytic approaches.

We have sought to improve the electrocatalytic performance of tungsten nitride through synthetic control over chemical composition and morphology. In particular, we have generated a thermodynamically unstable but catalytically promising nitrogen-rich phase of tungsten via a hydrothermal generation of a tungsten oxide intermediate and subsequent annealing in ammonia. The net product consisted of three-dimensional (3D) micron-scale flower-like motifs of W₂N₃; this architecture not only evinced high structural stability but also incorporated the favorable properties of constituent two-dimensional nanosheets. From a performance perspective, as-prepared 3D W₂N₃ demonstrated promising hydrogen evolution reaction (HER) activities, especially in an acidic environment with a measured overpotential value of -101 mV at a current density of 10 mA/cm². To further enhance the electrocatalytic activity, small amounts of precious metal nanoparticles (such as Pt and Au), consisting of variable sizes, were uniformly deposited onto the underlying 3D W₂N₃ motifs using a facile direct deposition method; these composites were applied towards the CO₂ reduction reaction (CO₂RR). A highlight of this series of experiments was that Au/W₂N₃ composites were found to be a much more active HER (as opposed to either a CO₂RR or a methanol oxidation reaction (MOR)) catalyst.