Biphasic Nanoalloys-Based Trifunctional Monolith for High-Performance Flexible Zn-Air Batteries and Self-Driven Water Splitting

Sufficient integration of multiple active moieties and correlated heterostructure engineering are pivotal to optimize the reaction kinetics and the intrinsic activities of heterogeneous electrocatalysts. Herein, an integrated heterostructure of biphasic nanoalloys are constructed, encasing in in situ grown and interlaced nitrogen-doped carbon nanoflake arrays (CoFe-NiFe/NC). Well-designed CoFe-NiFe/NC owns more accessible active sites and interfacial conjugation effects, jointly accelerating the electron transfer and mass transport for multifunctional electrocatalysis. Such unconventional monolith delivers extraordinary trifunctional activities for hydrogen evolution reaction, oxygen evolution reaction (overpotential of 185 mV at 10 mA cm-2) and oxygen reduction reaction. The superior trifunctionality of CoFe-NiFe/NC is rationalized with experimental and theoretical elucidation. Results reveal that the modulated electronic synergism between the Ni, Fe-assisted Co sites and the adjacent N-bridged carbon matrix decisively favors the appropriate binding of intermediates for promoted redox kinetics. Consequently, stand-alone CoFe-NiFe/NC cathode contributes to high-performance aqueous/flexible zinc-air batteries (ZABs), exhibiting high power/specific energy and excellent cycling stability. Remarkably, CoFe-NiFe/NC-based alkaline water electrolyzer requires merely 1.51 V to reach 10 mA cm-2, and a self-driven water splitting system yields a high H2 evolution rate. This unique heterostructure monolith would open up opportunities for developing high-efficiency multifunctional catalysts and advanced energy utilization devices. An integrated heterostructure monolith of biphasic nanoalloys encasing in interlaced N-doped carbon nanoflake arrays is rationally constructed. Such unconventional catalyst delivers extraordinary hydrogen evolution reaction (HER)/oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) activities due to more accessible active sites and reinforced interfacial conjugation. The crafted multifunctional catalyst demonstrates superiority for high-performance rechargeable/flexible Zn-air batteries, water electrolyzer and self-powered water splitting. image