Designing and facilely synthesizing a series of cobalt nitride (Co4N) nanocatalysts as non-enzymatic glucose sensors: A comparative study toward the influences of material structures on electrocatalytic activities

Designing high-efficiency electrocatalysts for glucose concentration detection plays a pivotal role in developing various non-enzymatic glucose detection devices. Herein, we have successfully designed and synthesized various cobalt nitrides (Co4N) by using different weak bases (i.e. hexamethylenetetramine (HMT), urea, and ammonium hydroxide (AH)) through nitridation treatment in ammonia (NH3) atmosphere. Physical characterization results demonstrate that Co4N-NSs (nanosheets) with vast meso/macropores and large BET surface are successfully constructed once adding carbon paper and HMT into precursors. As the synergistic effect of metallic character of Co4N phase, excellent electroconductibility of pyrolytic carbon, and large surface area, Co4N-NSs surfaces can form more Co4+ active sites in electrochemical reaction processes. Meanwhile, the abundant meso/macroporous structures constructed in Co4N-NSs further promoted its mass transfer ability. Benefitting from the above mentioned advantages, Co4N-NSs therefore exhibit more excellent glucose oxidation ability than another three control samples (i.e. Co4N-HMT, Co4N-Urea and Co4N-AH). When used for glucose detection, the optimal Co4N-NSs display excellent detection parameters as well, such as: a wide linear range of 0.6-10.0 mM, a large sensitivity of 1137.2 uA cm(-2) mM(-1) glucose, a low detection limit of 0.1 mu M, a small response time of 1.7 s, good reproducibility and stability, and the excellent anti-interference to other electroactive molecules and Cl-. Upon utilized for measuring glucose concentrations in human blood serum samples, the detection results on Co4N-NSs are accurate and satisfying as well. This work opens a new possibility for boosting electrochemical catalysis abilities of Co4N samples by the structure design.