Synthesis and electrochemical capacitive performance of thieno[3,4-b]pyrazine-based Donor-Acceptor type copolymers used as supercapacitor electrode material

[Display omitted] •Two novel TPZ and thiophene based polymers were applied as supercapacitor materials.•The electron donating capacity has markedly effect on the polymers capacitance.•Both polymers exhibited excellent and competitive capacitive performance. Two novel donor-acceptor-donor type monomers were synthesized by using thieno[3,4-b]pyrazine (TPZ) as the acceptor units (A) and 3-methylthiophene or 3-methoxythiophene as the donor units (D). The as-prepared D-A-D monomers were named as MOTP and MTP, respectively. These two monomers could be facilely polymerized on the glass carbon electrode (GCE) via a potentiostatic method, and the resultant D-A-D alternative conjugated polymers were referred as PMOTP and PMTP. The obtained conjugated polymers were routinely characterized by FT-IR, SEM and TGA at first. Then, as supercapacitor electrode materials, they were further investigated in detail by cyclic voltammetry (CV), constant galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) methods The GCD results showed that the polymer-modified GCEs had high specific capacitances of 678.2 and 319.1F/g, for PMOTP and PMTP, respectively, at a current density of 1A/g. Excellent switching stabilities were also observed for both polymer-modified GCEs, with the high retention rates of 77.3% and 53.4% for PMOTP and PMTP, respectively, after 1000 times of charge-discharge cycling at a current density of 10A/g. Notably, the maximum energy densities of 22.4Wh/kg and 7.94Wh/kg were attained at the power density of 0.55kW/kg for the symmetric supercapacitor based on PMOTP and PMTP, respectively. The excellent performances of these two D-A-D type conjugated polymers make them to be the promising electrode materials for energy-storage and conversion applications.