Highly Efficient Tandem Electrosynthesis of Dimethyl Carbonate From CO2.

Current DMC production is energy-intensive, while generating CO2 emissions. Electrosynthesis of DMC from CO2 offers a sustainable alternative but faces challenges of inert CO2 activation and unfavorable C-O coupling, leading to low selectivity and current density. Herein, we propose a tandem electrocatalysis strategy for efficient DMC production from CO2 under ambient conditions, utilizing a cobalt polyphthalocyanine framework (CoPPc) with single-atom sites and atomically precise palladium-sulfur clusters (Pd6S12). The CoPPc-Pd6S12 tandem catalyst system synergistically activates CO2 and enhances mass transport, elevating the local concentration of key intermediates (CO and methoxy species) for improving DMC production efficiency. Thus, the tandem system delivers exceptional performance with 93.4% DMC selectivity and 34.9 mmol L-1 h-1 production in 0.1 M NaBr methanol electrolyte, while achieving a recorded current density of 155.2 mA cm-2 at 0.5 M electrolyte concentration. In situ generated CO and methoxy over CoPPc efficiently transfer to the Pd-S site, where achieves intermediate stabilization and optimal coupling orientation, boosting DMC selectivity and current density. Moreover, DFT calculations reveal that the CoPPc-Pd6S12 system reduces the energy barrier for C-O coupling, facilitating DMC formation. This work provides an efficient tandem electrocatalysis system for DMC production from CO2 with high selectivity and large current density.