N, S co-doped lignin-based carbon microsphere functionalized graphene hydrogel with ‘‘sphere-in-layer” interconnection as electrode materials for supercapacitor and molecularly imprinted electrochemical sensors

This work reports a three-dimensional N, S co-doped lignin-based carbon microsphere/graphene composite hydrogel (GH-NSCMS) as an electrode material for supercapacitors and a signal enhancement material for tetracycline molecularly imprinted electrochemical sensors (MIECS). As a supercapacitor electrode, GH-NSCMS electrode has a specific capacitance of 434.6 F g −1 at 0.5 A g −1 , which can still maintain 94.15% after 5,000 cycles. In addition, a highly sensitive MIP electrochemical sensor for tetracycline detection is prepared based on GH-NSCMS composite material due to the synergistic effects of the high recognition accuracy of the imprinting method, and excellent conductivity of the composite hydrogel material. The sensor has a wide linear range (0.1–50 μM) and a significant detection limit (5 × 10 −8  mol L −1 ). Therefore, the 3D GH-NSCMS composites described herein have potential application prospects in supercapacitor electrode materials and tetracycline molecular imprinting detection.