A highly stable pyridinic nitrogen doped graphene (pyridine-NG) was used as an excellent electrocatalyst for the construction of electrochemical sensor for simultaneous determination of hydroquinone (HQ) and catechol (CC) in 0.20 M pH 5.5 acetate buffer solution. At the pyridine-NG modified electrode, both HQ and CC can cause a pair of quasi-reversible redox peaks and the potential difference of oxidation peaks between HQ and CC was 103 mV. Under the optimized condition, the oxidation peak current of HQ was linear over the range from 5 to 200 μM in the presence of 100 μM CC, and the oxidation peak current of CC was linear over the range from 5 to 200 μM in the presence of 100 μM HQ. The detection limit is 0.38 μM for HQ and 1 μM for CC (S/N = 3). This proposed sensor was successfully applied to the simultaneous determination of HQ and CC in artificial sample, and the results were good stability and high reproducibility. The excellent electrocatalysis of pyridine-NG can be due to the π–π interactions between the benzene ring of CC and graphene layer, the hydrogen bonds formed between hydroxyl in HQ molecule and pyridinic nitrogen atoms within graphene layers, especially the less density distribution of π electron cloud in pyridinic-NG in acidic condition.
