Spider nest shaped multi-scale three-dimensional enzymatic electrodes for glucose/oxygen biofuel cells

A spider nest shaped multi-scale three-dimensional substrate consisting of reduced graphene oxide (RGO) and nickel foam is fabricated for enzymatic electrodes and biofuel cells. According to the excellent conductivity and large electroactive surface area of this special structure, the enzymatic electrodes show large enzymatic loading density, low electron transfer resistance and high electrocatalytic efficiency. The strong forces in the spider nest shaped structure and the excellent enzymatic embedding method ensure the stability of the glucose oxidase bioanodes and laccase biocathodes. The Michaelis–Menten constant value for the bioanodes to glucose is calculated to be 2.24 mM, which is close to the Michaelis–Menten constant for free glucose oxidase, implying a remarkably high enzymatic activity. Employed the obtained bioelectrodes with great properties, the relative glucose/oxygen biofuel cell has an open-circuit voltage of 0.70 V, with a high output power performance, and a maximum output power of 7.05 ± 0.05 mW cm−2, owe to the high enzyme loading and low electron transfer resistance of the electrode based on the spider nest shaped structure. After 60 days of periodic storage experiments, the performance of the biofuel cell still maintained 84.2%, showing a good long-term stability.