A cathode electrode for a gas diffusion electrolytic flow cell that produces a carbon dioxide reduction product by reducing carbon dioxide, wherein the cathode electrode comprises a catalyst layer having a metal complex catalyst, a carbon material and an alkali metal salt, and a gas diffusion layer disposed on the catalyst layer.

A method for controllably making catalysts with at least one metallic surface state, that includes: a) identifying all the topological insulators in the ICSD, b) calculating the Real Space Invariants of the valence bands for all these topological insulators in order to c) identify in all these topological insulators the Wyckoff Positions where the irreducible Wannier Charge Centers (WCCs) are localized, and then d) selecting as potentially catalytic active compound a topological insulator in which the position of WCCs is not occupied by any atom; e) synthesizing a crystal of the selected potentially catalytic active compound either so that it is grown in a predefined crystallographic direction (characterized by its Miller indices (h,k,l)) which exposes the metallic surface state; or cutting the crystal in a predefined crystallographic direction (characterized by its Miller indices (h,k,l)), so that the metallic surface state is exposed when

[00001]$\left(\left(\{\begin{array}{c}\left(h,k,l\right).Math.\left(x-X_j,y-Y_j,z-Z_j\right)=0,\\ \left(h,k,l\right).Math.\left(x-x_i,y-y_i,z-z_i\right)\ne 0,\\ h,k,lϵZ\end{array}\right)\right)$

To improve the efficiency of a reduction reaction. A power source applies a voltage to an oxidation electrode immersed in an aqueous solution in an oxidation tank and a reduction electrode immersed in an aqueous solution in a reduction tank, the voltage having a voltage value that changes with a predetermined cycle to be a voltage value at which ions can be desorbed from a surface of the oxidation electrode and a surface of the reduction electrode during one cycle of the voltage change. The frequency of the voltage is set within a range of 10 Hz to 1 kHz.

A device for catalytic conversion of carbon dioxide (CO.sub.2) includes a substrate having a surface, an array of conductive projections supported by the substrate and extending outward from the surface of the substrate, each conductive projection of the array of conductive projections having a semiconductor composition, and a plurality of nanoparticles disposed over the array of conductive projections, each nanoparticle of the plurality of nanoparticles being configured for the catalytic conversion of carbon dioxide (CO.sub.2). Each nanoparticle of the plurality of nanoparticles includes a metal sulfide, the metal sulfide including a d-block metal.

A device for catalytic conversion of carbon dioxide (CO.sub.2) includes a substrate having a surface, an array of conductive projections supported by the substrate and extending outward from the surface of the substrate, each conductive projection of the array of conductive projections having a semiconductor composition, and a plurality of nanoparticles disposed over the array of conductive projections, each nanoparticle of the plurality of nanoparticles being configured for the catalytic conversion of carbon dioxide (CO.sub.2). Each nanoparticle of the plurality of nanoparticles includes a metal sulfide, the metal sulfide including a d-block metal.

The electrochemical carbon dioxide reduction reaction (CO.sub.2RR) provides opportunities to synthesize value-added products from this greenhouse gas in a sustainable manner. Efficient catalysts for this reaction are provided that selectively drive CO.sub.2 reduction over the thermodynamic and kinetically competitive hydrogen evolution reaction (HER) in organic or aqueous electrolytes. The catalysts are metal-polypyridyl coordination complexes of a redox non-innocent terpyridine-based pentapyridine ligand and a first-row transition metal. The metal-ligand cooperativity in [Fe(tpyPY2Me)].sup.2+ drives the electrochemical reduction of CO.sub.2 to CO at low overpotentials with high selectivity for CO.sub.2RR (>90%).

The electrochemical carbon dioxide reduction reaction (CO.sub.2RR) provides opportunities to synthesize value-added products from this greenhouse gas in a sustainable manner. Efficient catalysts for this reaction are provided that selectively drive CO.sub.2 reduction over the thermodynamic and kinetically competitive hydrogen evolution reaction (HER) in organic or aqueous electrolytes. The catalysts are metal-polypyridyl coordination complexes of a redox non-innocent terpyridine-based pentapyridine ligand and a first-row transition metal. The metal-ligand cooperativity in [Fe(tpyPY2Me)].sup.2+ drives the electrochemical reduction of CO.sub.2 to CO at low overpotentials with high selectivity for CO.sub.2RR (>90%).

A flow-through electrolysis cell includes a hierarchical nanoporous metal cathode. A method of reducing CO.sub.2 includes flowing the CO.sub.2 through the hierarchical nanoporous metal cathode of the flow-through electrolysis cell.

A flow-through electrolysis cell includes a hierarchical nanoporous metal cathode. A method of reducing CO.sub.2 includes flowing the CO.sub.2 through the hierarchical nanoporous metal cathode of the flow-through electrolysis cell.

Electrochemical conversion of CO.sub.2 to formic acid or a salt thereof, using an indium containing catalytic electrode, comprising (a) electrochemically converting CO.sub.2 to formic acid or a salt thereof by applying a voltage to an electrochemical cell comprising the catalytic electrode as cathode and an anode, wherein the electrochemical cell is fed with an electrolyte comprising CO.sub.2; and (b) regenerating the catalytic electrode by lowering the voltage and subsequently washing the catalytic electrode with an aqueous liquid and exposing the catalytic electrode to air without applying voltage; and (c) optionally repeating steps (a) and (b).