TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - The photo-electrochemical cell comprises a first photocatalytic unit adapted to receive the moistened gas and to photo-oxidize water of the moistened gas into oxygen and a second photocatalytic unit adapted to receive CO2 or a gas comprising CO2 and to photocatalytically reduce CO2, where the first photocatalytic unit comprises a photocatalytic material that is interconnected by a positive charge (protons H+) transport means with photocatalytic material of a second photocatalytic unit and further comprising connected by an electron transport means where the interconnected first photocatalyst and second photocatalyst form an anode and cathode electrode when receiving radiation from a radiation source. It is a single-cell fuel cell where when operational the both types of photocatalytic electrodes are irradiated. Second photocatalyst electrode adapted to photocatalytically reduce CO2 or plurality second electrodes adapted to photocatalytically reduce CO2 are at least in part coated with a layer of CO2 absorbing material such layer being adapted to absorption of CO2 from an atmosphere, for instance from air. The layer of CO2 absorbing material comprises metal-organic framework material (MOF's). The MOF is selected from MOF-177, MOF-5 and IRMOF-1. Layer of CO2 absorbing material comprises a CO2 absorbing molecular sieve. The CO2 absorbing molecular sieve is a Zeolite 5A. Layer of CO2 absorbing material is 3-4 nm thick. At least one radiation means is a UV and/or visible light transparent window adapted to irradiation both the first and the second electrodes or the photocatalyst materials. At least one radiation means is a quartz glass window adapted to irradiation both the first photocatalytic unit and the second photocatalytic unit. First photocatalyst electrode or electrodes are transparent and where the at least one radiation means is an UV and/or visible light transparent window adapted to directly irradiation the first transparent electrode or electrodes and indirectly though the first transparent electrodes the second photocatalyst electrodes. Second photocatalyst electrode or electrodes are transparent and where the at least one radiation means is an UV and/or visible light transparent window adapted to directly irradiation the second transparent electrode or electrodes and indirectly though the second transparent electrodes the first photocatalyst electrodes. Charge transport means comprises a material for instance a membrane to allow movement of cations but where the material does not conduct anions or electrons nor is permeable for gasses. Both the anode and the cathode or both the first electrode and second electrode comprise a graphene coated carbon fabric, for instance a graphene sheet on carbon fabric. The charge transport means comprises a Nafion membrane. It comprises a Teflon membrane doped with Nafion polymer. The proton transport is enhanced by means of conducting polymers like polypyrrole or polyimidazoles. The first electrode or electrodes or the photo-catalytic-oxidation anode adapted to photo-oxidize water comprises titanium dioxide catalyst nanoparticles grafted on the electrode. Titanium dioxide catalyst is coated with silver to enhance the affinity to the visible light spectrum. The catalytic properties are modified by adding metal particles, for instance particles of an Fe element and at least one element selected from V, Nb, Ta, Cr, Mo, W, Mn, Tc, and Re or a metal particle composed of a combination of Fe and Mo, Fe and Cr, Fe and Ce, Fe and Mn or the like. The graphene sheets are doped, preferably with boron, to enhance the electron capture ability. Second electrode or electrodes or photocatalytic cathode adapted for reduction of CO2 comprises purely N-doped graphene sheets. Second electrode or electrodes or photocatalytic cathode adapted for reduction of CO2 comprises N-doped (nitrogen doped) carbon nanotubes in combination with a p-type semiconductor of gallium phosphide (GaP), copper oxide (Cu2O), silicon carbide (SiC) and nickel oxide (NiO). Second electrode or electrodes or photocatalytic cathode adapted for reduction of CO2 comprises N-doped (nitrogen doped) carbon nanotubes and/or N-doped graphene sheets in combination with a p-type semiconductor of GaP, Cu2O, SiC and NiO. Graphene sheet is amine (NH3) treated for the incorporation of N-atoms in the sheets. Addition to the N-doping, a p-type GaP semiconductor is used for a selective reduction of CO2. The photo-electrochemical cell a single-cell fuel cell where the radiation means to irradiate both types of photocatalytic electrodes is a window made in quartz glass. It further comprises an electronic controller to control the potential of the photocatalytic electrodes. It comprises an electronic controller for maintaining the potential of both types of photocatalytic electrode at a constant level. The cell further comprises an electronic controller adapted to control the electrochemical reactions. Electronic controller is a potentiostat for instance a VersatSTAT. It is a bipotentiostat. The photo-electrochemical cell comprises at least one unit comprising at least two flow trough compartments; this unit is at least in part formed by an encapsulation means or a cover means and a sequence or stack of layers of positive charge (protons H+) transport means between the first photocatalyst material to photo-oxidize water, and the second photocatalyst material to photocatalytically reduce CO2 further characterized in that the compartments of the unit are at least in part formed by a outer wall of encapsulation means or a cover means and an inner photocatalyst material , where the first compartment that is at least in part formed by an encapsulation means and a first photocatalyst material to photo-oxidize water and the second compartment is at least in part formed by an encapsulation means and a second photocatalyst material to photocatalytically reduce CO2. Encapsulation means comprises a radiation means. It is at least in part a radiation means. Radiation means comprises or is a window at least partially transparent to a wavelength of light. Radiation means comprises or is a window transparent to a wavelength of light capable of driving the photocatalytic process. It comprises or is a light transporter for transporting light from a light source for instance the sun or a lamp towards the photocatalyst. The photo-electrochemical cell comprises light transporters (for instance mirrors) configured to transfer, transmit or reflect light to the surface of such photocatalytic reactor materials. It comprises a light transporter to direct natural light external to the photo- electrochemical cell into the interior of the photo-electrochemical cell to illuminate the photo catalytic materials; a light transporter to direct through a tube assembly natural light external to the photo-electrochemical cell into the interior of the photo- electrochemical cell to illuminate the photocatalytic materials; a light transporter to more efficiently transmit or reflect light from a medium to the photocatalytic materials or surfaces; or a light transporter to transport light to the photocatalyst reactors for water splitting or and the photocatalyst reactors for CO2 reduction. Radiation means is foreseen by a wave length converter to improve the quantum efficiency at the photocatalysator or the surfaces to the photocatalytic material. The photo-electrochemical cell comprises an irradiation source; an irradiation source which is sunlight; an artificial light source; and transparent material for instance a glass window adapted by a serpentine flow profile to provide optimal gas delivery to the electrodes and/or carry away reacted products. EXAMPLE - No example given.