Fabrication of Poly (Trans-3-(3-Pyridyl)Acrylic Acid)/Multi-Walled Carbon Nanotubes Membrane for Electrochemically Simultaneously Detecting Catechol and Hydroquinone.

Herein, conductive polymer membrane with excellent performance was successfully fabricated by integrating carboxylated multi-walled carbon nanotubes (MWCNTs) and poly (trans-3-(3-pyridyl) acrylic acid) (PPAA) film. The drop-casting method was employed to coated MWCNTs on the glassy carbon electrode (GCE) surface, and PPAA was then electropolymerized onto the surface of the MWCNTs/GCE in order to form PPAA-MWCNTs membrane. This enables the verification of the excellent performances of proposed membrane by electrochemically determining catechol (CC) and hydroquinone (HQ) as the model. Cyclic voltammetry experiments showed that the proposed membrane exhibited an obvious electrocatalytic effect on CC and HQ, owing to the synergistic effect of PPAA and MWCNTs. Differential pulse voltammetry was adopted for simultaneous detection purposes, and an increased electrochemical responded to CC and HQ. A concentration increase was found in the range of 1.0 × 10-6 mol/L~1.0 × 10-4 mol/L, and it exhibited a good linear relationship with satisfactory detection limits of 3.17 × 10-7 mol/L for CC and 2.03 × 10-7 mol/L for HQ (S/N = 3). Additionally, this constructed membrane showed good reproducibility and stability. The final electrode was successfully applied to analyze CC and HQ in actual water samples, and it obtained robust recovery for CC with 95.2% and 98.5%, and for HQ with 97.0% and 97.3%. Overall, the constructed membrane can potentially be a good candidate for constructing electrochemical sensors in environmental analysis.

Pollen-derived porous carbon decorated with cobalt/iron sulfide hybrids as cathode catalysts for flexible all-solid-state rechargeable Zn-air batteries.

The development of flexible all-solid-state rechargeable Zn-air batteries (FS-ZABs) for wearable applications faces challenges from the balance between performance and flexibility of the battery; efficient cathode catalyst and reasonable electrode construction design are key factors. Herein, a low-cost pollen derived N,S co-doped porous carbon decorated with Co9S8/Fe3S4 nanoparticle hybrids (Co-Fe-S@NSRPC) has been synthesized. Owing to the active Co9S8/Fe3S4 nanoparticles, N,S co-doping, and large specific area of the pollen derived porous carbon matrix, the Co-Fe-S@NSRPC composite exhibits an excellent bifunctional catalytic activity with a small potential gap (ΔE = 0.80 V) between the half-wave potential for the ORR (0.80 V) and the potential at 10 mA cm-2 for the OER (1.60 V), and endows a liquid Zn-air battery with a high power density of 138 mW cm-2, a larger specific capacity of 891 mA h g-1 and a stable rechargeability of up to 331 cycles. Based on the Co-Fe-S@NSRPC cathode catalyst, a 2D coplanar FS-ZAB has been fabricated with specially designed parallel narrow strip electrodes alternately arrayed on a polyacrylamide polyacrylic acid copolymer hydrogel solid electrolyte. The presented FS-ZAB exhibits excellent battery performance with high open-circuit-voltage (1.415 V), competitive peak power density (78 mW cm-2), large specific capacity (785 mA h g-1) and stable rechargeability (150 cycles), offers robust flexibility to maintain stable charge/discharge capacity under different bending deformations, and provides convenient coplanar integrability to realize parallel or series connection of multiple cells in a relatively small area.