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Efficient and Stable TiO 2 :Pt–Cu(In,Ga)Se 2 Composite Photoelectrodes for Visible Light Driven Hydrogen Evolution
Author(s) -
Azarpira Anahita,
Lublow Michael,
Steigert Alexander,
Bogdanoff Peter,
Greiner Dieter,
Kaufmann Christian A.,
Krüger Martin,
Gernert Ullrich,
van de Krol Roel,
Fischer Anna,
SchedelNiedrig Thomas
Publication year - 2015
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201402148
Subject(s) - materials science , photocurrent , anatase , chalcopyrite , composite number , electrolyte , electrode , thin film , water splitting , chemical engineering , hydrogen , conductivity , optoelectronics , photocatalysis , nanotechnology , copper , catalysis , composite material , metallurgy , biochemistry , chemistry , organic chemistry , engineering
Novel thin film composite photocathodes based on device‐grade Cu(In,Ga)Se 2 chalcopyrite thin film absorbers and transparent conductive oxide Pt‐implemented TiO 2 layers on top are presented for an efficient and stable solar‐driven hydrogen evolution. Thin films of phase‐pure anatase TiO 2 are implemented with varying Pt‐concentrations in order to optimize simultaneously i) conductivity of the films, ii) electrocatalytic activity, and iii) light‐guidance toward the chalcopyrite. Thereby, high incident‐photon‐to‐current‐efficiencies of more than 80% can be achieved over the full visible light range. In acidic electrolyte (pH 0.3), the most efficient Pt‐implemented TiO 2 –Cu(In,Ga)Se 2 composite electrodes reveal i) photocurrent densities up to 38 mA cm −2 in the saturation region (−0.4 V RHE, reversible hydrogen electrode), ii) 15 mA cm −2 at the thermodynamic potential for H 2 ‐evolution (0 V RHE), and iii) an anodic onset potential shift for the hydrogen evolution (+0.23 V RHE). It is shown that the gradual increase of the Pt‐concentration within the TiO 2 layers passes through an efficiency‐ and stability‐maximum of the device (5 vol% of Pt precursor solution). At this maximum, optimized light‐incoupling into the device‐grade chalcopyrite light‐absorber as well as electron conductance properties within the surface layer are achieved while no degradation are observed over more than 24 h of operation.