NOVELTY - A photocatalytic material comprising a colloidal semiconductor nanocrystal (202); and a photocatalytic capping agent (206, 208) that binds to a surface of the semicondutor nanocrystal (302, 304), is new. The photocatalytic capping agent is an inorganic capping agent.    USE - As photoactive material in the reduction of carbon dioxide (claimed) for producing fuel such as methane.    ADVANTAGE - The nanocrystals within the photoactive material exhibit higher efficiency of solar energy conversion process. The synthesis of the photocatalytic material is flexible as one capping agent may be chosen for its growth control properties, and then later a different capping agent may be substituted to provide a more suitable interface or to modify optical properties or charge carrier mobility. The photocatalytic material comprises semiconductor nanocrystals having different morphologies i.e. nanocrystals, nanorods, nanoplates, nanowires, nanotubes, dumbbell-like nanoparticles, and dendritic nanomaterials which include an additional variety of shapes spherical, tetrapod, core/shell or tetrahedron. The selection of morphology and size of semiconductor nanocrystals permits the tuning and control of the properties of photocatalytic capped colloidal nanocrystals.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a photocatalytic capped collodial nanocrystal comprising a first semiconductor nanocrystal (302), a second semiconductor nanocrystal (304) bonded to the first semiconductor nanocrystal, a first inorganic capping agent (206) that caps the first semiconductor nanocrystal, and a second inorganic capping agent (208) that caps the second semiconductor nanocrystal; and    (2) preparing the photocatalytic capped collodial nanocrystal involving: a)reacting a semiconductor nanocrystal precursor and an organic solvent to produce organic capped semiconductor nanocrystals in a non-polar solution; b)dissolving the inorganic capping agent in an immiscible, polar solvent to form a polar solution; c)combining the polar and the non-polar solutions in a reaction vessel; d)replacing the organic capping agent with the inorganic capping agent to form inorganic capped semiconductor nanocrystals (C1); e)purifying (C1); depositing (C1) on a porous substrate; f)heating the deposited (C1) thermally; and g)annealing to form inorganic matrices with embedded photocatalytic capped colloidal nanocrystals.    DESCRIPTION OF DRAWING(S) - The figure shows a view of nanorod configuration of photocatalytic capped colloidal nanocrystals.    Photocatalytic capped collodial nanocrystal (202)    First inorganic capping agent (206)    Second inorganic capping agent (208)    First semiconductor nanocrystal (302)    Second semiconductor nanocrystal (304)