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

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.

An electrode of a chemical cell 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 for reduction of carbon dioxide (CO.sub.2) in the chemical cell, and a catalyst arrangement disposed along each conductive projection of the array of conductive projections, the catalyst arrangement including a copper-based catalyst and an iron-based catalyst for the reduction of carbon dioxide (CO.sub.2) in the chemical cell.

An electrode of a chemical cell 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 for reduction of carbon dioxide (CO.sub.2) in the chemical cell, and a catalyst arrangement disposed along each conductive projection of the array of conductive projections, the catalyst arrangement including a copper-based catalyst and an iron-based catalyst for the reduction of carbon dioxide (CO.sub.2) in the chemical cell.

An electrode of a chemical cell 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 for reduction of carbon dioxide (CO.sub.2) in the chemical cell, and a catalyst arrangement disposed along each conductive projection of the array of conductive projections, the catalyst arrangement including a copper-based catalyst and an iron-based catalyst for the reduction of carbon dioxide (CO.sub.2) in the chemical cell.

An electrode of a chemical cell 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 for reduction of carbon dioxide (CO.sub.2) in the chemical cell, and a catalyst arrangement disposed along each conductive projection of the array of conductive projections, the catalyst arrangement including a copper-based catalyst and an iron-based catalyst for the reduction of carbon dioxide (CO.sub.2) in the chemical cell.

A gas-phase reduction device for carbon dioxide includes: an oxidation chamber containing an oxidation electrode; a reduction chamber to which carbon dioxide is supplied; a gas reduction sheet that has an ion exchange membrane and a reduction electrode laminated together therein and that is disposed between the oxidation chamber and the reduction chamber with the ion exchange membrane facing the oxidation chamber and the reduction electrode facing the reduction chamber; a conducting wire that connects the oxidation electrode and the reduction electrode; and a heat source that surrounds the reduction chamber.

A gas-phase reduction device for carbon dioxide includes: an oxidation chamber containing an oxidation electrode; a reduction chamber to which carbon dioxide is supplied; a gas reduction sheet that has an ion exchange membrane and a reduction electrode laminated together therein and that is disposed between the oxidation chamber and the reduction chamber with the ion exchange membrane facing the oxidation chamber and the reduction electrode facing the reduction chamber; a conducting wire that connects the oxidation electrode and the reduction electrode; and a heat source that surrounds the reduction chamber.

A light-driven fuel cell includes a cathode, an anode, and a proton-permeable membrane between the anode and the cathode. The anode includes a photocatalyst for anaerobic methane oxidation reaction, and when the anode is supplied with methane and water and is irradiated with light, methanol, protons and electrons are generated by anaerobic methane oxidation reaction from the methane and the water supplied to the anode; the protons pass through the proton-permeable membrane and move to the cathode; and the electrons move to the cathode via an external circuit. The cathode includes a photocatalyst for aerobic methane oxidation reaction, and when the cathode is supplied with methane and oxygen and is irradiated with light, methanol and water are generated by aerobic methane oxidation reaction from the methane and the oxygen supplied to the cathode and the protons and the electrons moved from the anode.

A light-driven fuel cell includes a cathode, an anode, and a proton-permeable membrane between the anode and the cathode. The anode includes a photocatalyst for anaerobic methane oxidation reaction, and when the anode is supplied with methane and water and is irradiated with light, methanol, protons and electrons are generated by anaerobic methane oxidation reaction from the methane and the water supplied to the anode; the protons pass through the proton-permeable membrane and move to the cathode; and the electrons move to the cathode via an external circuit. The cathode includes a photocatalyst for aerobic methane oxidation reaction, and when the cathode is supplied with methane and oxygen and is irradiated with light, methanol and water are generated by aerobic methane oxidation reaction from the methane and the oxygen supplied to the cathode and the protons and the electrons moved from the anode.