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Cu2O/gas diffusion layer (GDL) electrodes prepared by electrodeposition were studied for the electrocatalytic reduction of CO2. The designed electrode was also tested in solar‐light‐induced CO2 conversion in combination with a CuO/NtTiO2 photoanode using a compact photoelectrocatalytic (PEC) cell. Both PEC cell electrodes were prepared using non‐critical raw materials and low cost, easily scalable procedures. In the PEC experiments, a total carbon faradaic selectivity of about 90 % to formate and about 75 % to acetate was obtained after 24 h of operations without application of potential/current or using sacrificial agents. In electrocatalytic tests of CO2 reduction at −1.5 V, the same electrode yielded high total faradaic selectivity (>95 %) but formed selectively formate (about 80 % selectivity) rather than acetate. The in situ transformation of the Cu2O/GDL electrode leads to the formation of a hybrid Cu2O–Cu/GDL system. Cyclic voltammetry data indicate that the potential and the presence of CO2 (not only of HCO3− species) are both important elements in this transformation. Data also indicate that the surface concentration of CO2 (or of its products of transformation) on the electrode is an important factor to determine performance in the conversion of CO2. [ABSTRACT FROM AUTHOR]

The effect of current density on product distribution and yield in the electrochemical reduction of carbon dioxide was studied by processing low-cost and non-critical raw materials. Specifically, the electrodes were prepared by depositing copper (Cu) nanoparticles on functionalized carbon nanotubes (CNTs), then assembled with a gas diffusion layer and a proton exchange membrane. The as-prepared electrodes were fully characterized by different advanced techniques to study their morphological and structural characteristics, as well as their electrochemical properties. Finally, the electrodes were tested in the process of CO2 electroreduction by using a compact electrochemical device, designed on purpose to minimize overpotential phenomena. The tests were carried out under a continuous flow of pure CO2 in 0.1 M KHCO3 as the electrolyte, applying different voltages (from -0.5 to -1.7 V vs. Ag/AgCl) in order to obtain different current densities (from 0.1 to 2.3 mA cm-2, respectively). Furthermore, tests under industrial relevant conditions (high current density) were performed by providing directly 10 mA cm-2 to the working electrode. Results showed that current density strongly influences the product distribution, with formic acid and CO being the main products at high current density, while products like methanol, ethanol, isopropanol, acetic acid, and oxalic acid were formed at lower applied potential. [ABSTRACT FROM AUTHOR]

Sol immobilization is a relevant preparation method, particularly for the preparation of Pd‐based catalysts for the direct synthesis of H2O2. In this preparation, polyvinyl alcohol (PVA) acts as capping agent for Pd particles. Modelling the role of PVA on the Pd nanoparticle size and its promoting effect on the selectivity is important to understand better these catalysts. Here, Pd based catalysts prepared by sol immobilization have been tested in a semi‐batch reactor with an H2/O2 ratio ≈1, analysing the influence of the Pd nanoparticle size and the effect of PVA on the rate constants of the reaction network and their change during the reaction. A stepwise testing protocol coupled with transmission electron microscopy characterization as a function of reaction time has been used. These catalysts were compared with other catalysts prepared by hydrazine reduction and impregnation‐decomposition, where PVA is absent. The results are analysed in terms of rate constants for the various rates in the reaction network in relation with the Pd average particle size and related sites distribution, as a function of the changes occurring during extended catalytic tests. The SI‐series of catalysts (prepared by sol‐immobilization) shows enhanced properties, attributed to the effect of PVA capping agent in forming less defective Pd nanoparticles. This induces both a decrease of direct combustion and secondary hydrogenolysis reactions, and an enhancement of the direct synthesis route. The PVA layer limits H2O2 back‐diffusion with a negative influence on the productivity and selectivity, with its removal leading to initial enhanced performances, but in long‐term to a worsening due to sintering of Pd nanoparticles in extended operations. Straight to the point: The role of polyvinyl alcohol (PVA) capping agent for Pd nanoparticles active in H2O2 direct synthesis is studied and kinetically modelled to single out the different effects in modifying the catalytic performances. PVA enhances the properties leading to less defective Pd nanoparticles, inducing both a decrease of direct combustion and secondary hydrogenolysis reactions, and an enhancement of the direct synthesis route. [ABSTRACT FROM AUTHOR]

From a personal view, this perspective analyses the gaps and opportunities for catalysis to address the electrification of chemical production from a high-tech scenario. It is assumed that a significant substitution of fossil fuels is required to meet the net-zero emissions targets. This vision significantly impacts the future of catalysis and sustainable chemical production. We identified short (up to 2030), medium- (2030–2040) and long-term (2040–2050) objectives for catalysis. Novel catalytic routes of direct manufacturing chemicals and fuels using renewable energy should be developed. These are mainly based on photo-, electro- and plasma-catalysis, indicated shortly as "reactive" catalysis. Their common characteristic is that reactive species generated in these processes provide the energy to overcome the activation barriers. They differentiate from conventional heterogeneous catalysis, where the energy for the catalytic transformation is given by heat and thus indicated as "thermal" catalysts. The main priority in the short-term scenario is the design of novel "thermal" catalysts to exploit the new opportunities given by the electrification of chemical reactors. The innovation related to exploiting the novel possibilities offered by i) structured temperature gradients inside the reactor and ii) operations under fast dynamic temperature control. The medium-term challenge is direct electrification to produce chemicals and fuels, including energy vectors. Their development generates the bases for future carbon-neutral chemical production. Accelerating this innovative transformation requires identifying critical issues and focusing research on them. In the longer term, the necessity of artificial-leaf-type solutions is remarked. They should integrate all the necessary functionalities, including operations without a separate unit to capture/purify the reactants (such as N 2 or CO 2). These solutions will be an enabling tool for a distributed production of chemicals and fuels. [Display omitted] • Catalysis scenario for carbon-neutral chemical production. • From "thermal" to "reactive" catalysis. • Catalysis for electrified chemical reactors. • Catalysis for direct electrified chemical synthesis. • Catalysis to substitute the use of fossil fuels. [ABSTRACT FROM AUTHOR]