Toward an Effective Control of the H₂ to CO Ratio of Syngas through CO₂ Electroreduction over Immobilized Gold Nanoparticles on Layered Titanate Nanosheets

In recent years, the electroreduction of CO₂ to valuable products has emerged as a rational answer to rising CO₂ emissions and a strategic approach to incorporate renewable electricity from intermittent sources (e.g., wind and solar) into the global energy supply. The reduction of CO₂ to CO has been highlighted in the widely explored industrial conversion of syngas (CO and H₂) to fuels. Herein, we report a promising electrocatalyst incorporating well-dispersed gold nanoparticles (Au NPs) on ultrathin titanate nanosheets (TiNS). By tuning the contents of Au (in the ranges of 0 to 93 wt % Au) in the hybrid Au/TiNS architecture, CO product selectivity was effectively controlled (in the range of CO Faradaic efficiency from 3 to over 80%) with the sole additional formation of H₂, which is of pronounced industrial interest. Most importantly, a control of both component amounts was suggested to result in a variation of corresponding electronic properties based on the interaction between Au NP and TiNS substrate, dictating the stabilization of formed reaction intermediates and resulting product selectivity. In addition, our Au/TiNS achieved optimally high CO and H₂ production current densities, with 73 wt % Au at the low cathodic potential region (-0.6 to -0.9 V_RHE). The suggested synergetic effect between both catalytic components underlines the promising character of this hybrid system and is expected to significantly add to the strategic production of syngas for subsequent applications.