Synthesis of morphology-controlled N-doped porous carbon for simultaneous electrochemical sensing of dihydroxybenzene isomers

Different morphology of N-doped carbon materials, including three-dimensional interconnected N-doped hierarchically porous carbon networks (3D-NC), two-dimensional ultrathin porous carbon nanosheets (2D-NC), and bulk N-doped carbon with micron size (bulk-NC), was easily prepared by using NaCl crystal templates-assisted strategy. Compared with bare glassy carbon, bulk-NC, and 2D-NC, the as-synthesized 3D-NC exhibits excellent electrochemical activity toward the oxidation and sensing of three kinds of common environmental pollutants dihydroxybenzene isomers (hydroquinone (HQ), catechol (CC), and resorcinol (RS)). The impressive electrochemical activity of 3D-NC can be interpreted by its large specific surface area, continuous network-like morphology, superior electro-catalytic ability, and strong accumulation efficiency. Differential pulse voltammetry (DPV) test showed the 3D-NC-modified electrode exhibited three well-separated oxidation peaks at 0.05 V, 0.14 V, and 0.45 V vs. saturated calomel electrode (SCE) for HQ, CC, and RS, and their detection limits were evaluated to be as low as 0.0044, 0.012, and 0.016 mg L-1, respectively. Finally, a novel electrochemical analytical platform is successfully fabricated for the simultaneous monitoring of hydroquinone, catechol, and resorcinol with high sensitivity. When used for real wastewater samples analysis, recovery ratio ranging from 94 to 108% with lower than 5% of relative standard deviation (RSD) values was achieved. This work proves a facile strategy to prepare morphology-controlled N-doped carbon-based material and demonstrates its high application potential for environmental monitoring and electrochemical analysis.