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 (Co 4 N) by using different weak bases ( i.e. hexamethylenetetramine (HMT), urea, and ammonium hydroxide (AH)) through nitridation treatment in ammonia (NH 3 ) atmosphere. Physical characterization results demonstrate that Co 4 N-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 Co 4 N phase , excellent electroconductibility of pyrolytic carbon , and large surface area , Co 4 N-NSs surfaces can form more Co 4+ active sites in electrochemical reaction processes. Meanwhile, the abundant meso/macroporous structures constructed in Co 4 N-NSs further promoted its mass transfer ability. Benefitting from the above mentioned advantages, Co 4 N-NSs therefore exhibit more excellent glucose oxidation ability than another three control samples ( i.e. Co 4 N-HMT, Co 4 N-Urea and Co 4 N-AH). When used for glucose detection, the optimal Co 4 N-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   µM, 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 Co 4 N-NSs are accurate and satisfying as well. This work opens a new possibility for boosting electrochemical catalysis abilities of Co 4 N samples by the structure design.