NOVELTY - Use of at least one organometallic complex of platinum with at least one ligand having a cyclic structure comprising at least two non-adjacent double bonds (C=C), or cyclic structure with two ligands each comprising double bond (C=C), or two ligands with cyclic structure comprising each double bond (C=C) and ligand, as a precursor for chemical vapor deposition of platinum silicide surface of a support, is claimed.    USE - The organometallic complex is useful as a precursor for the chemical vapor deposition of platinum silicide surface of a support, which is useful in proton exchange membrane fuel cells (all claimed). The catalytic layer is useful for: treating, in air, the pollutants such as volatile organic compounds and nitrogen oxides; generation of hydrogen by reforming of hydrocarbons, biomass fuel or storage of hydrogen by adsorption and filtration of water.    ADVANTAGE - The organometallic complex exhibits improved chemical stability and increased electroactive surface; and provides high electrocatalytic activity and performance to the proton exchange membrane fuel cells.    DETAILED DESCRIPTION - Use of at least one organometallic complex of platinum with at least one ligand having a cyclic structure comprising at least two non-adjacent double bonds (C=C), or cyclic structure with two ligands each comprising double bond (C=C), or two ligands with cyclic structure comprising each double bond (C=C), and ligand comprising silicon compound of formula (a1-O-Si(R)3) (a) or (a1-N-(Si(R1)3)2) (b), as a precursor for the chemical vapor deposition of platinum silicide surface of a support, is claimed.    R = 1-4C-alkoxy;    R1 = 1-4C-alkyl or 3-4C-cycloalkyl; and    a1 = platinum coordination ligand.    INDEPENDENT CLAIMS are included for:    (1) forming a catalytic layer based on the platinum silicide surface of the support, comprising performing chemical vapor deposition of platinum silicide in the solid support surface with the organometallic compounds of platinum;    (2) the support having a catalyst layer containing platinum silicide, where at least 20 wt.%, preferably at least 40 wt.% of the platinum forming electroactive surface of the layer, and the platinum is present in a coordinated form with silicon; and    (3) proton exchange membrane fuel cells comprising the support having the catalyst layer.