Gold nanoparticle decoration of insulating boron nitride nanosheet on inert gold electrode toward an efficient electrocatalyst for the reduction of oxygen to water

• Overpotential for oxygen reduction reaction is reduced by AuNP decoration of BNNS.
• The AuNP decoration of BNNS opens a 4-electron oxygen reduction route to water.
• Importance of stabilization of adsorbed oxygen atom by AuNP is shown theoretically.

Overpotential for oxygen reduction reaction (ORR) at Au electrode is reported to be reduced by 0.27 V by the modification with boron nitride nanosheet (BNNS) but oxygen is reduced only to H2O2 by 2-electron process at Au electrode. Here we demonstrate that the decoration of BNNS with gold nanoparticles (AuNP) not only reduces the overpotential for ORR further by ca. 50 mV, but also opens a 4-electron reduction route to water. Both rotating disk electrode experiments with Koutecky–Levich analysis and rotating ring disk electrode measurements show that more than 50% of oxygen is reduced to water via 4-electron process at Au–BNNS/Au electrode while less than 20 and 10% of oxygen are reduced to water at the BNNS/Au and bare Au electrodes, respectively. Theoretical analysis of free energy profiles for ORR at the BN monolayer with and without Au8 cluster placed on Au(111) shows significant stabilization of adsorbed oxygen atom by the Au8 cluster, opening a 4-electron reduction pathway.

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