Bioelectrochemical systems (BES) possess great potential for simultaneous wastewater treatment and energy recovery.

Cobalt phthalocyanine (CoPc) has attracted particular interest owing to its excellent activity during the electrochemical CO2 conversion to CO. However, the efficient utilization of CoPc at industrially relevant current densities is still a challenge owing to its nonconductive property, agglomeration, and unfavorable conductive substrate design. Here, a microstructure design strategy for dispersing CoPc molecules on a carbon substrate for efficient CO2 transport during CO2 electrolysis is proposed and demonstrated. The highly dispersed CoPc is loaded on a macroporous hollow nanocarbon sheet to act as the catalyst (CoPc/CS). The unique interconnected and macroporous structure of the carbon sheet forms a large specific surface area to anchor CoPc with high dispersion and simultaneously boosts the mass transport of reactants in the catalyst layer, significantly improving the electrochemical performance. By employing a zero‐gap flow cell, the designed catalyst can mediate CO2 to CO with a high full‐cell energy efficiency of 57% at 200 mA cm−2.

In article number 2300051, Qian Fu and co-workers report a microstructure design strategy for dispersing CoPc molecules on macroporous hollow nanocarbon sheets in CO 2 electrolysis. The carbon sheets' interconnected and macroporous structure provides a large surface area for anchoring CoPc with high dispersion and promotes reactant mass transport, thus improving the catalytic performance.