Superior Oxygen Reduction Reaction on Phosphorus-Doped Carbon Dot/Graphene Aerogel for All-Solid-State Flexible Al–Air Batteries

Carbon dots have been recognized as one of the most promising candidates for the oxygen reduction reaction (ORR) in alkaline media. However, the desired ORR performance in metal–air batteries is often limited by the moderate electrocatalytic activity and the lack of a method to realize good dispersion. To address these issues, herein a biomass-deriving method is reported to achieve the in situ phosphorus doping (P-doping) of carbon dots and their simultaneous decoration onto graphene matrix. The resultant product, namely P-doped carbon dot/graphene (P-CD/G) nanocomposites, can reach an ultrahigh P-doping level for carbon nanomaterials. The P-CD/G nanocomposites are found to exhibit excellent ORR activity, which is highly comparable to the commercial Pt/C catalysts. When used as the cathode materials for a primary liquid Al–air battery, the device shows an impressive power density of 157.3 mW cm⁻² (comparing to 151.5 mW cm⁻² of a similar Pt/C battery). Finally, an all-solid-state flexible Al–air battery is designed and fabricated based on our new nanocomposites. The device exhibits a stable discharge voltage of ≈1.2 V upon different bending states. This study introduces a unique biomass-derived material system to replace the noble metal catalysts for future portable and wearable electronic devices.