Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a promising conductive polymer material, but its acidic nature leads to device deterioration and poor long-term durability. It is usual practice to neutralise PEDOT:PSS solutions with bases, resulting in a decrease of conductivity. The causes of the decline in conductivity remain disputed and uncertain. In this study, three bases (sodium hydroxide, ammonium hydroxide, and imidazole) were employed to treat PEDOT:PSS to investigate their effects on doping level, composition, and structure. The results show that bases may dedope PEDOT:PSS by removing the proton doping from the PEDOT chain. Meanwhile, insulating PSS is removed, and the aggregated structure is optimised to ensure that conductivity is not significantly reduced. The PEDOT:PSS treated with the weak base imidazole showed the least loss of conductivity due to only a modest decrease in doping level and the greatest loss of insulating PSS. Aluminium electrolytic capacitors made using imidazole pH-adjusted solutions have a capacitance ratio of up to 98.28% and an equivalent series resistance of 26 mΩ. These findings provide a valuable reference for developing high electrical characteristics and neutral PEDOT:PSS materials.
Rongcheng Peng,Yang Gao,Hussein A. Younus,Yan Zhang,Wenpeng Ni,Shiguo Zhang
Upgrading CO2 to formate systems is a promising avenue for fuel production, and SnOx is a unique low-cost candidate for this conversion. However, the high oxygen affinity of Sn sites leads to a strong adsorption of O-bound intermediates, resulting in a low efficiency of CO2 reduction. Herein, density functional theory (DFT) calculations confirmed that a H-doping strategy of SnO2 produces partially depleted positive charge Sn sites, weakening the adsorption of HCOO* and boosting the electron transfer kinetics. Experimentally, H-doped commercial SnO2 nanoparticles (H-SnO2) indeed had enhanced intrinsic activity for CO2-to-formate conversion with suppressed hydrogen evolution performance. Remarkably, H-SnO2 achieves over 90.0% formate selectivity within −0.6 to −1.0 V (vs RHE) at the industrial current density of 220 mA cm–2. Electrochemical measurements and in situ Raman spectra analysis together disclosed that H-doping speeds up the kinetic rate for the first electron transfer of CO2 reduction and also promotes formate desorption, resulting in the impressively high current density and selectivity of H-SnO2.
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