Boron-doped diamond dual-plate microtrench electrode for generator–collector chloride/chlorine sensing

• A method for fabricating diamond double electrodes with new plate–plate geometry
• SU-8 protocol is simple, rapid and generally applicable and could be optimised further
• The electrode enables fast feedback redox-cycling via generator–collector approach
• New route to direct detection of chloride/chlorine under harsh anodic conditions
• New opportunities for generator–collector analysis not possible on metal or ITO
• Electroanalysis on collector electrode (free of capacitive components) up to + 2.25 V

A novel generator–collector dual-plate boron-doped diamond microtrench sensor is fabricated and its operation demonstrated for chloride/chlorine detection in the harsh anodic potential range. Detection is made sensitive by minimising the inter-electrode gap to ≤ 10 μm wide and setting the generator and collector potentials to enable repetitive redox cycling. The concentration and potential-dependant impact on the generator and collector currents are reported and optimised conditions suitable for quantitative determination are demonstrated. The diffusional redox cycling currents for chloride in buffer solution are kinetically controlled and first order over a concentration range of 1 to 140 mM.

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