Bio-based activated carbons with very high specific surface area of >3.000 m² g⁻¹ (based on CO₂ adsorption isotherms) and a high proportion of micropores (87% of total SSA) are produced by corncobs via pyrolysis and chemical activation with KOH. The activated carbon is further doped with different proportions of the highly pseudocapacitive transition metal oxide RuO₂ to obtain enhanced electrochemical properties and tune the materials for the application in electrochemical double-layer capacitors (EDLC) (supercapacitors). The activated carbon and composites are extensively studied regarding their physico-chemical and electrochemical properties. The results show that the composite containing 40 wt.% RuO₂ has an electric conductivity of 408 S m⁻¹ and a specific capacitance of 360 Fg⁻¹. SEM-EDX, XPS, and XRD analysis confirm the homogenous distribution of partly crystalline RuO₂ particles on the carbon surface, which leads to a biobased composite material with enhanced electrochemical properties.

In metrology, the certification of potassium hydrogen phthalate (KHP) as a reference material is made using the potential primary method of coulometric titration. Usually, this titration is performed in three steps at constant current, where two endpoint (EP) times are determined from the nonlinear regression that fits the empirical W-function (eWf) to the experimental data. As an alternative, we propose the implementation of the theoretical coulometric titration curve (TC). The TC allowed us to compute the KHP amount of substance, the influence of CO2 in the system, the acid dissociation constants for carbonic and phthalic acids, assuming that those species are the only acids present during titration, and the EP times. The amount of substance of KHP estimated with the EP time and obtained from the TC was compared with the results of the eWf, and no statistical difference was found, while the amount of substance, when estimated directly as a parameter of the nonlinear regression of the TC, was lower. Therefore, the traditional method finds the total acidity of the dissolution, and our method finds the KHP purity. In addition, the acid dissociation constants for H2CO3 and phthalic acid estimated in this work agreed with the data reported in the literature. Finally, the description of the coulometric system using the theoretical TC has a solid and well-known chemical support that is not present in the eWf; this fact is essential for the uncertainty budget and the scientific support for coulometry as a potential primary method.