Reduction of carbon dioxide at copper(I) oxide photocathode activated and stabilized by over-coating with oligoaniline

Photoelectrochemical Reduction of CO2 at Poly(4‐Vinylpyridine)‐Stabilized Copper(I) Oxide Semiconductor: Feasibility of Interfacial Decoration with Palladium Cocatalyst

“…Finally, modification of the copper(I) oxide deposit with the protective P4VP polymer overlayer has not changed the oxidation state of copper because the Raman Cu 2 O characteristic peaks still exist. On the contrary, the presence of the peaks that could be assigned to copper(I) oxide (Figure 1D), rather than their absence (as in a case of the dense coherent oligoaniline overlayers on Cu 2 O), [ 34 ] would imply the existence of less condensed films in the present case. It should be remembered that the P4VP polyelectrolyte tends to form porous submicrometer (typically on the level of 200–400 nm) films on common electrode substrates.…”

“…Among p‐type semiconducting copper‐containing transition metal oxides, copper(I) oxide (Cu 2 O), which is nontoxic and characterized by a direct bandgap of ≈2 eV permitting illumination with solar light, is a good candidate for photocathode. [ 24,27,30–34 ] Here, as in the case of transition metal oxides, the interfacial oxygen vacancies have been suggested to function as the active sites for CO 2 adsorption and activation. Unfortunately, Cu 2 O is susceptible to reductive decomposition or photocorrosion.…”

“…Among important strategies is the interfacial modification of the semiconductor's surface (e.g., with polymer films, catalytic metals, molecular nanostructures, or plasmonic nanoparticles) typically resulting in the improvement of stability, in addition to better control of selectivity or increase in activity of the photocathode. [ 23–40 ] As in conventional electrocatalysis, the introduction of an appropriate catalyst or cocatalyst should lead to the activation of the initial high‐energy‐barrier reduction of CO 2 to CO 2 •− , to better control of CO 2 and the reaction intermediates, or even to providing trapping sites for electrons, thus improving charge separation at the photoelectrochemical interface.…”

“…[ 44 ] Among important features is that the polymer has pyridine groups in chains with weakly basic N atoms exhibiting reactivity toward coordination of transition metals, [ 41 ] capability of interacting with copper(I) surfaces, [ 45 ] and immobilization of catalytic (or cocatalytic) centers. [ 46 ] It is noteworthy that conducting polymers, [ 34,47–49 ] particularly those having N atoms, are efficient in lowering the CO 2 activation energy through effective trapping of CO 2 molecules, and they are attractive candidates for inducing CO 2 electroreduction. When P4VP has been used as a gas separation membrane in the copper‐based gas diffusion electrode, the CO 2 reduction faradaic efficiency has increased due the pH sensitivity of the polymer, thus affecting the selectivity of the investigated copper catalyst.…”

Visible-light-driven CO2reduction on dye-sensitized NiO photocathodes decorated with palladium nanoparticles

“…Copper-based oxides have been investigated as CO 2 RR photocathodes but their instability caused by photoelectrochemical corrosion tends to limit their practical applications. [14][15][16]18,[20][21][22][23][24] On the other hand, NiO is thermally and chemically stable and resists photocorrosion upon illumination. 25,26 It has been used as a protective overlayer in photoanodes for solar fuel generation applications.…”