Potential-induced sonoelectrochemical graphene nanosheets with vacancies as hydrogen peroxide reduction catalysts and sensors

Defective graphene nanosheets (dGN(4V)) with 5-9, 5-8-5, and point defects were synthesised by a sonoelectrochemical method, where a potential of 4 V (vs. Ag/AgCl) was applied to drive the rapid intercalation of phosphate ions between the layers of the graphite foil as a working electrode. In addition to these vacancies, double vacancy defects were also created when the applied potential was increased to 8 V (dGN(8V)). The defect density of dGN(8V) (2406 μm(−2)) was higher than that of dGN(4V) (1786 μm(−2)). Additionally, dGN(8V) and dGN(4V) were applied as catalysts for the hydrogen peroxide reduction reaction (HPRR). The mass activity of dGN(8V) (1.31 × 10(−2) mA·μg(−1)) was greater than that of dGN(4V) (1.17 × 10(−2) mA·μg(−1)) because of its high electrochemical surface area (ECSA, 1250.89 m(2)·g(−1)) and defect density (N(D), 2406 μm(−2)), leading to low charge transfer resistance on the electrocatalytic interface. The ECSA and N(D) of dGN(4V) were 502.7 m(2)·g(−1) and 1786 μm(−2), respectively. Apart from its remarkable HPRR activity, the cost-effective dGN(8V) catalyst also showed potential as an amperometric sensor for the determination of H(2)O(2).