Microwave‐assisted control of PtNi nanoalloy clusters on the nitrogen‐doped graphene oxide for energy conversion with oxygen reduction reaction and hydrogen evolution reaction

Research on the production and utilization of hydrogen energy is essential to overcome the environmental issues caused by fossil fuels. Herein, we anchor PtNi nanoalloy clusters (Pt‐Ni NACs) on nitrogen‐doped graphene oxide (NrGO) by a facile microwave‐assisted synthesis and analyze the variations of catalyst properties based on the PtNi composition and the presence of nitrogen. Ni inclusion in the Pt matrix can induce lattice strain and change the electronic structure, while the doped nitrogen into the graphene can enhance electron transfer and improve the durability of the catalyst through strong chemical bonding with the alloy clusters. TEM analysis discovers that the NACs are uniformly decorated in a few‐nanometer‐size on the graphene surface, and the formation of the PtNi NACs and structural changes according to composition are confirmed through XRD and XPS. In addition, the structural changes due to N‐doping and its bonding with the NACs are observed through Raman spectroscopy and XPS. Electrochemical measurements reveal that Pt2.6Ni NACs/NrGO exhibits the highest ORR onset potential (0.893 V) and the lowest HER overpotential at 10 mA cm−2 (22 mV) among other catalysts, and those activities are almost unchanged under long‐term durability tests. From these results, Pt2.6Ni NACs/NrGO is utilized in a zinc‐air battery (ZAB) system, demonstrating better battery performance than commercial Pt and Ir‐based catalysts. Moreover, it is applied to hydrogen collection, showing linear trend in hydrogen production over time, confirming the catalyst's availability in hydrogen production and utilization. A few nanometer‐sized PtNi NACs are uniformly decorated on NrGO. Structural changes are observed depending on the PtNi composition, N‐doping on the graphene surface, and chemical bonding between N sites and NACs. Pt2.6Ni NACs/NrGO exhibits the highest ORR onset potential (0.893 V) and the lowest HER overpotential at 10 mA cm−2 (22 mV). From these results, Pt2.6Ni NACs/NrGO is applied to both ZAB system and hydrogen collection to assess its availability.