Photovoltaic Electrochemically Driven Degradation of Calcon Dye with Simultaneous Green Hydrogen Production

Abstract

In this study, for the first time, the production of green hydrogen gas (H2) in the cathodic compartment, in concomitance with the electrochemical oxidation (EO) of an aqueous solution containing Calcon dye at the anodic compartment, was studied in a PEM-type electrochemical cell driven by a photovoltaic (PV) energy source. EO of Calcon was carried out on a Nb/BDD anode at different current densities (7.5, 15 and 30 mA cm−2), while a stainless steel (SS) cathode was used for green H2 production. The results of the analysis by UV-vis spectroscopy and total organic carbon (TOC) clearly showed that the electrochemical oxidation (EO) of the Calcon dye after 180 min of electrolysis time by applying 30 mA cm−2 reached up to 90% of degradation and 57% of TOC removal. Meanwhile, under these experimental conditions, a green H2 production greater than 0.9 L was achieved, with a Faradaic efficiency of 98%. The hybrid electrolysis strategy is particularly attractive in the context of a circular economy, as these can be coupled with the use of more complex water matrices to transform organic depollution into an energy resource to produce H2 as a chemical energy carrier.

A sustainable solar-driven electrochemical process for reforming lignocellulosic biomass effluent into high value-added products: green hydrogen, carboxylic and vanillic acids

“…This behavior is due to the use of the electrical charge for anodic reactions and the existence of the fuel crossover and internal currents phenomena, in the former stage, which is a typical effect. 71 …”

“…Approximately 0.12, 0.08 and 0.06 L as well as 0.095, 0.082 and 0.065 L of H 2 were produced in 60 min of electrolysis from the EO of methyl red dye and 2,4-dichlorophenoxyacetate in aqueous solutions respectively for the non-active anodes, PbO 2 , Si/BDD and Sb-doped SnO 2 anodes, respectively. 75 Meanwhile, the green H 2 volume produced in a hybrid process (with a Ni–Fe-based mesh as cathode) with simultaneous EO of Calcon dye 71 in the anodic compartment with the BDD anode was approximately 0.3 L by applying 30 mA cm −2 at 25 °C. From these results, it is possible to infer that, the production of H 2 is dependent on the surface area of the anode material, cathode nature and the electrical requirements ( i.e.…”

“…This behavior is due to the use of the electrical charge for anodic reactions and the existence of the fuel crossover and internal currents phenomena, in the former stage, which is a typical effect. 71 Another important aspect that we must take into consideration is H 2 energy efficiency. This parameter in electrolysis systems can be dened as the heating value of hydrogen versus the rate of hydrogen produced (mol h −1 ) divided by the energy consumed by the electrolyzer, reecting improved thermodynamic operating conditions (eqn ( 7)).…”

Photo-assisted electrochemical CO2 reduction at a boron-doped diamond cathode

“…15 This may help produce energy with a lower environmental impact, 16–18 as in the case of hydrogen production from water electrolysis. 19–22…”

“…15 This may help produce energy with a lower environmental impact, [16][17][18] as in the case of hydrogen production from water electrolysis. [19][20][21][22] In a (photo)electrochemical system, energy efficiency is affected by several energy losses, mainly ascribed to the electrochemical cell (e.g., ohmic drop, electrolyte, mass transport, and separators), 23,24 which can be reduced by a careful engineering design, and the overpotential that is intrinsic for the reaction and electrocatalyst/electrode materials used. In particular, when a reduction reaction is coupled with the oxygen evolution reaction (OER) from water oxidation, this 4-electron reaction may account for the largest loss of energy in the electrochemical system due to overpotential.…”