A method for manufacturing a cross-linked carbon nanomaterial, said process comprising the steps of: a) providing a carbon nanomaterial; and b) contacting said carbon nanomaterial with a solution comprising an acyl halide in an aprotic solvent in order to obtain a cross-linked carbon nanomaterials. An electrode comprising a layer of acylated cross-linked carbon nanomaterial and an electrically conductive element. A fuel cell comprising said electrode, a counter electrode and an electrolyte. A cross-linked acylated carbon nanomaterial.