Nanostructure Engineering and Electronic Modulation of a PtNi Alloy Catalyst for Enhanced Oxygen Reduction Electrocatalysis in Zinc–Air Batteries

Abstract

PtNi nanoalloys have demonstrated electrocatalysis superior to that of benchmark Pt/C catalysts for the oxygen reduction reaction (ORR), yet the underlying mechanisms remain underexplored. Herein, a PtNi/NC catalyst comprising PtNi nanoparticles (∼5.2 nm in size) dispersed on N-doped carbon frameworks was prepared using a simple pyrolysis strategy. Benefiting from the individual components and a hierarchical structure, the PtNi/NC catalyst exhibited outstanding ORR activity and stability (E 1/2 = 0.82 V vs RHE and 8 mV negative shift after 20000 cycles), outperforming a commercial 20 wt % Pt/C catalyst (E 1/2 = 0.81 V and 32 mV negative shift). A prototype zinc–air battery constructed using PtNi/NC as the air electrode catalyst achieved highly enhanced electrochemical performance, outperforming a battery constructed using Pt/C as the ORR catalyst. Density functional theory calculations revealed that the improved ORR activity of the PtNi nanoalloys originated from charge redistribution with a suitable metal d-band center to promote the formation of the ORR intermediates.

Improving Oxygen Reduction Reaction Performance of Pt by a N-Doping Strategy and Inducing Tensile Strain of Nanoparticles

“…24 There are also bimetallic site catalysts, such as PtCo/NC, PtNi/NC, and so on. 25,26 The above works lowered the reaction free energy of the ORR after modulation of the binding energy of O 2 and oxygenated intermediates, thus boosting the ORR activity.…”

“…Recently, tremendous research efforts have been devoted to exploring nitrogen-doped carbon materials and have achieved remarkable results. − For instance, Liu et al reported a high-performance and durable carbon-supported Pt 1 –N/BP catalyst ( E 1/2 of 0.87 V in 0.1 M KOH), DFT calculations indicated that the single-pyridinic-N-anchored single Pt atom centers are the main active sites . There are also bimetallic site catalysts, such as PtCo/NC, PtNi/NC, and so on. , The above works lowered the reaction free energy of the ORR after modulation of the binding energy of O 2 and oxygenated intermediates, thus boosting the ORR activity.…”

l-Alanine-Assisted Synthesis of a Hierarchically Porous Co@N–C/N-Ketjenblack Carbon Catalyst for Oxygen Reduction in Zn–Air Batteries

“…1,2 However, the practical energy capacity of ZABs is presently much lower than the theoretical value and one of the main reasons for it is the sluggish kinetics of four-electrontransfer oxygen reduction reaction (ORR) that occurs on the air cathode during battery discharge. 3,4 Currently, Pt-based catalysts are typically used in ZABs to drive the ORR. However, the high cost, scarcity, and poor stability of Pt-based catalysts represent obstacles to the widespread application of ZABs.…”

“…Zinc–air batteries (ZABs) are presently attracting a lot of interest as a power due to their high theoretical specific energy capacity (1086 W h kg –1 ), inherent safeness, non-toxicity, and low cost. , However, the practical energy capacity of ZABs is presently much lower than the theoretical value and one of the main reasons for it is the sluggish kinetics of four-electron-transfer oxygen reduction reaction (ORR) that occurs on the air cathode during battery discharge. , Currently, Pt-based catalysts are typically used in ZABs to drive the ORR. However, the high cost, scarcity, and poor stability of Pt-based catalysts represent obstacles to the widespread application of ZABs. − Hence, the discovery of highly efficient non-precious metal-based electrocatalysts for ORR is an imperative. − …”

Sodium Tartrate-Assisted Synthesis of High-Purity NiFe2O4 Nano-Microrods Supported by Porous Ketjenblack Carbon for Efficient Alkaline Oxygen Evolution

“…Dwindling fossil-fuel reserves, together with environmental damage caused by the burning of fossil-fuels for energy, demand the rapid development of renewable energy technologies. − Hydrogen represents a very promising energy carrier to replace fossil-fuels due to its high energy density and zero carbon emissions when used in hydrogen fuel cells. − Electrochemical water splitting using renewably generated electricity is widely regarded as the most promising and viable route for high-purity hydrogen production at scale. − The anodic reaction in overall water splitting is the oxygen evolution reaction (OER), a sluggish four-electron-transfer process that typically requires a high overpotential to drive it. − To achieve a high electrical energy utilization efficiency and lower the overpotential, efficient OER electrocatalysts are indispensable. − To date, expensive precious metal oxide-based catalysts, such as RuO 2 and IrO 2 , offer the best OER activity. , However, these catalysts suffer from poor durability under alkaline OER conditions. These factors motivate the search for alternative, low-cost, high activity, and durable OER catalysts to replace RuO 2 and IrO 2 . − …”