TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The matrix components are linked to one another and to the conductive surface. The photocatalytic element is: derived from a natural source; and an isolated natural photosystem complex. The photocatalytic element is photosystem I complex, photosystem II complex or bacterial reaction center. At least one photocatalytic element is directly associated with at least one noble metal nanoparticle, which is ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and/or gold. The electrode comprises at least one connecting group associated with at least one of the nanoparticle, the photocatalytic element and conductive surface, preferably at least two connecting groups being same or different. The connecting group is an electropolymerized oligomer, which comprises at least one aromatic or heteroaromatic moiety.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The electropolymerized oligomer comprises at least two anchoring groups which may be the same or different and are each independently chemically associated with at least one of the nanoparticle, photocatalytic element and conductive surface. The connecting group is substituted aromatic moiety of formula (Z1-L-Z2) (I). The connecting group connecting the noble metal nanoparticle to the photocatalytic element of the composite matrix is of formula (Z3-L1-Z4) (II). The connecting group connecting the matrix composite to the conductive surface is of formula (Z5-L2-Z6) (III). The composite matrix further comprises at least one electron acceptor group, preferably ferredoxin and/or ferredoxin. The electrode further comprises at least one compound capable of mediating the electron transfer of the photocatalytic element. Preferred Process: The electropolymerizing step is performed in the presence of the electron acceptor molecule chemically associated with the electropolymerizable group of formula (Z10-L6) (VII).Z1, Z2 = bond or moiety chemically associated with at least one of the nanoparticle, photocatalytic element and conductive surface;L = linker group comprising at least one electropolymerized monomer or its oligomer, preferably thioaniline, thiophenol, aminothiophenol, and/or thiopyrrole;L1, L2 = linker group comprising at least one electropolymerized monomer or its oligomer;Z3, Z4 = bond or moiety chemically associated with at least one of the nanoparticle of the composite matrix and photocatalytic element;Z5, Z6 = bond or moiety chemically associated with at least one of the nanoparticle of the composite matrix, photocatalytic element and conductive surface;Z10 = bond or moiety that is chemically associated with the electron acceptor molecule; andL6 = linker group comprising the electropolymerized monomer or its oligomer. EXAMPLE - No suitable example given.