Nanostructured boron-doped diamond electrode for seawater salinity detection

Abstract Electrodes with high response and stability are urgently required to reach a steady and accurate measurement of seawater salinity. Herein, boron-doped diamond (BDD) is for the first time considered as a promising alternative to commercial platinum black in seawater salinity detection due to their considerable conductivity and outstanding stability. However, the intrinsical low double layer capacitance (DLC) of planar BDD film (BDDF) electrodes affect their response in the detection. To solve these problems, boron-doped diamond nanorod forest (BDDNF) electrodes are fabricated via hot filament chemical vapor deposition. Noted, four orders of magnitude larger of DLC (2820 μF/cm2) than BDDF (0.35 μF/cm2) is achieved on BDDNF due to a much enhanced electroactive surface area which is calculated to be 1.47 times larger than BDDF. Benefited from the enhanced DLC and accelerating diffusion resulted by the nanostructure, the response of BDDNF exhibits an enhancement by a factor of 1.5 compared to BDDF at the salinity of 40 ‰. Moreover, in striking contrast to commercial platinum black electrode, the obtained BDDNF electrodes exhibit outstanding stability thanks to the increased amount of carbon oxygen functional groups on BDDNF surface. This work greatly promises the potential applications of BDDNF electrodes in seawater salinity detection.