Direct electrosynthesis of 52% concentrated CO on silver’s twin boundary

The gaseous product concentration in direct electrochemical CO(2) reduction is usually hurdled by the electrode’s Faradaic efficiency, current density, and inevitable mixing with the unreacted CO(2). A concentrated gaseous product with high purity will greatly lower the barrier for large-scale CO(2) fixation and follow-up industrial usage. Here, we developed a pneumatic trough setup to collect the CO(2) reduction product from a precisely engineered nanotwinned electrocatalyst, without using ion-exchange membrane. The silver catalyst’s twin boundary density can be tuned from 0.3 to 1.5 × 10(4) cm(−1). With the lengthy and winding twin boundaries, this catalyst exhibits a Faradaic efficiency up to 92% at −1.0 V and a turnover frequency of 127 s(−1) in converting CO(2) to CO. Through a tandem electrochemical-CVD system, we successfully produced CO with a volume percentage of up to 52%, and further transformed it into single layer graphene film.