High-performance direct liquid fuel cells benefited from highly N-doped and defect-rich carbon paper cathode with carbon nanosheets

Persulfate is a potential oxidant in direct liquid fuel cells (DLFCs), and the commercial carbon paper (CP) can directly serve as the cathode due to strong oxidizability of persulfate. However, the poor catalytic activity and low specific surface area of CP limit the electrode performance. Herein, a defect-enriched, pyridine-N-dominated and self-standing carbon paper electrode with abundant carbon nanosheets is successfully prepared by hydrothermal treatment combined with in-situ electrochemical exfoliation. Benefitting from the integrated structure, plentiful defects and high-content pyridine-N dopants of the prepared electrode result in the superior electrocatalytic activity and long-term stability in persulfate reduction reaction. Remarkably, a membraneless DLFC with the prepared electrode as cathode and persulfate as the oxidant acquires prominent cell performance and extremely high open circuit voltage of 2.13 V. The maximum power density of the DLFC achieves 241.0 mW cm−2, far higher than those of the previously reported similar membraneless DLFCs. A three-dimensional computational model for the DLFC is developed, which is help to reveal the importance of improving the reaction kinetics and electrical conductivity for the cathode with persulfate as oxidant. A facile approach for in-situ preparation of highly N-doped CP electrode is provided to yield outstanding cell performance for low-cost DLFCs.