Multifunctional electrode materials based on brochantite for the fabrication of high-stability supercapacitors and dual-mode uric acid/17β-estradiol electrochemical sensors

Compared to other transition metal-based materials, copper-based materials are often neglected despite their several advantages, such as facile redox properties, high stability, and low cost. For the first time, novel electrode materials based on brochantite were tested as supercapacitors and uric acid/17β-estradiol sensors. Brochantite (Cu4SO4(OH)6) was synthesized using the one-step solvothermal method. Upon thermal annealing, it was converted to dolerophanite (Cu2O(SO4)) and copper (II) oxide (CuO). The composite electrodes, combining brochantite, dolerophanite, copper (II) oxide, and polyaniline, were prepared. Interestingly, the quaternary composite synergistically gave a specific capacitance as high as 376 F g−1 and a capacitance retention of 95.34 % after 10,000 cycles, which are much better than each of its parent compounds. The analysis of variance was performed to elucidate the relationship between the materials and specific capacitance. Furthermore, the novel brochantite/polyaniline composite electrode demonstrated superb electrochemical sensing activity for the simultaneous detection of uric acid and 17β-estradiol. Based on these findings, the composite electrodes based on brochantite can multi-function as high-performance supercapacitor components and for the dual-mode, simultaneous detection of uric acid and 17β-estradiol. This work will also open the door for the search for new copper-based materials for a variety of electrochemical applications.