ORIGINAL PAPER Facile electrochemical growth of nanostructured copper phthalocyanine thin film via simultaneous anodic oxidation of copper and dilithium phthalocyanine for photoelectrochemical hydrogen evolution R. S. Vishwanath 1 & Sakthivel Kandaiah 1 Received: 7 September 2015 /Revised: 11 December 2015 /Accepted: 15 December 2015 /Published online: 29 December 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract We present a novel electrochemical approach to grow copper phthalocyanine (CuPc) thin-film photoelectrodes through anodic oxidation of copper and dilithium phthalocya- nine (Li 2 Pc). This circumvents the challenges associated with the electrochemical processing of unsubstituted CuPc from so- lution. The potentiostatic co-electrooxidation reaction at the het- erogeneous interface favors the growth of CuPc thin film. The surface morphology of thin film exhibits nanorod-like features. UV-Vis, grazing angle Fourier transform infrared (FTIR), and grazing angle X-ray diffraction patterns reveal that the nanocrys- talline phase corresponds only to α-CuPc and no admixture of other polymorphs. Photocurrent measurement shows a stable photoresponse in neutral medium. The photoelectrochemical hydrogen evolution on p-type CuPc coated copper photocathode shows an enhanced activity over bare copper and indium tin oxide (ITO) electrodeposited with CuPc and monolithium phthalocyanine radical (LiPc) thin films. Keywords Photoelectrochemical hydrogen evolution . Electrodeposition . Photocathodes . Copper phthalocyanine . Dilithium phthalocyanine Introduction Solar energy conversion to solar fuels through photoelectrochemical process needs photoactive semiconductors fabricated as thin-film photoelectrodes [1–4]. Nanoarchitectures of photoelectrodes play a significant role on semiconductor/ electrolyte interface, efficient trapping of the visible part of the solar spectrum, and separation of photogenerated excitons. The long-term stability of the photoactive materials in a three- phase interface for hydrogen evolution is another vital require- ment in photoelectrochemical cells [4, 5]. Recently, p-type photoactive polymeric organic semiconductors and molecular photocatalysts as heterojunction with inorganic photoelectrodes were in focus to retard the recombination effects and to en- hance the effective separation of photogenerated charge car- riers [6–8]. The symmetrical phthalocyanine ligand is an im- portant model for biologically essential species such as chlo- rophyll, hemoglobin, and porphyrin [9, 10]. The remarkable physio-chemical stability, crystal structure features, and semi- conducting behavior of phthalocyanines have extended their application in many vital areas [9, 10]. CuPc is one of the important p-type semiconducting metallo-phthalocyanine (MPc) in the view of its physio-chemical stability, band gap (1.8 eV), and a bright cyan color. This is useful in solar cells, thin-film transistors, light-emitting diodes, and bio-sensing [11–14]. The photoelectrochemistry of many metal phthalocy- anines show a good visible light absorption and photoconduc- tivity [15]. It is observed that the photocurrent response of the thin films depends on the molecular ordering, thickness, and the redox characteristics of metal phthalocyanines [16, 17]. Mostly, these thin films were fabricated by physical methods and the photocurrent responses were studied in a dry cell setup [16, 17]. Electrochemical growth of unsubstituted MPcs as thin films from the solution remains seldom explored due to their solubility limitations [9, 10]. Hence, the thin films of CuPc were usually fabricated by high-temperature tech- niques, ultrahigh vacuum-organic molecular beam deposi- tion, spray coating, spin coating, and precipitation techniques. But, these techniques require the strict control on the thin-film * Sakthivel Kandaiah sakthivel@reva.edu.in 1 School of Chemical Sciences, REVA University, Bangalore, Karnataka 560064, India J Solid State Electrochem (2016) 20:767–773 DOI 10.1007/s10008-015-3107-1