NOVELTY - A material comprises a solid support of a conductive or semi-conductive material which is functionalized on its surface by linker arms containing at least two extremities, where the first extremity is bonded to the solid support either by a covalent link or via pi -stacking interaction and the second extremity is linked in a covalent manner to a metal-organic complex.    USE - In the electrode for water electrolyser, fuel cell (claimed) and photoelectrocatalytical (PEC) devices.    ADVANTAGE - The material is easy to prepare, based on cheap materials, and permits the economically viable production and oxidation of hydrogen gas, which implies a catalyst with a low activation potential, and a resistance to degradation under working conditions; improved stability; is use only a handful of metal atoms; has higher catalytic activity, thus reduces metallic charge; are very selective towards their chemical substrate, as opposed to platinum nanoparticles that are irreversibly polluted by gas or organic pollutants; and used metals are not necessarily noble metals.    DETAILED DESCRIPTION - A material comprises a solid support of a conductive or semi-conductive material which is functionalized on its surface by linker arms containing at least two extremities, where the first extremity is bonded to the solid support either by a covalent link or via pi -stacking interaction and the second extremity is linked in a covalent manner to a metal-organic complex, where the linker arm is selected from compound formulae (Ia), (Ib) and oligomers resulting from the oligomerization of compound (Ic).    Ar1=6-30C aromatic residue optionally comprising 1-6C alkyl, -OH, -NH2, -COOH, -F, -Cl, -Br, -I, -NO2, -CON(R'')2, -COOR'', -SO3, -SR'', -OR'', or -N(R'')2;    R and R'=H, 1-20C alkyl, 1-20C alkenyl, 1-20C alkynyl, 6-30C aryl, or 6-30C aralkyl optionally comprising -OH, -NH2, -COOH, -CONH2, triazole, -SH, -N3, and optionally interrupted by bridges selected from -CONH-, -CO-O-, -CO-O-CO-, -CO-NH-CO-, -CO-S-, -CS-O-, -CS-S-;    R''=H, 1-20C alkyl, 1-20C alkenyl, 1-20C alkynyl, 6-30C aryl, or 6-30C aralkyl;    X=1-20C alkyl, 1-20C alkenyl, 1-20C alkynyl, 6-30C aryl, 6-30C aralkyl optionally comprising OH, -NH2, -COOH, -CONH2, triazole, -SH, -N3, and optionally interrupted by bridges selected from CONH-, -CO-O-, -CO-O-CO-, -CO-NH-CO-,-CO-S-, -CS-O-, -CS-S-;    x=1-5;and    Y'=simple covalent link, -O-, -NH-,-S-, -COO-, -CONH-, -CO-S-, -CS-O-, or -CS-S-.    An INDEPENDENT CLAIM is included for electrode comprising the material deposited on a support of another conductive material.