Improved Water Oxidation Performance of Ultra-thin Planar Hematite Photoanode: Synergistic Effect of In/Sn doping and an Overlayer of Metal Oxyhydroxides
Artikel i vetenskaplig tidskrift, 2020

Hematite is a promising photoanode candidate with many favorable material properties, such as stability and suitable band-gap. However, there are some severe challenges, including high losses due to charge recombination and slow oxidation kinetics, which can be addressed by doping and addition of co-catalysts. Here, the effects of temperature driven diffusion of substrate impurities (doping) and subsequent surface modification by metal oxy-hydroxides (co-catalysts) have been studied for enhanced water-oxidation performance in photoelectrochemical (PEC) measurements. Diffusion of indium and tin from the indium-doped tin oxide (ITO) substrate into planar films of α-Fe2O3 photoanodes results in a photocurrent density (Jph) of 0.09 mA/cm2, corresponding to an approximate 9-fold enhancement over the control pristine α-Fe2O3 (0.01 mA/cm2) at 1.23 VRHE. A thin amorphous FeOOH coating over the In/Sn co-doped α-Fe2O3 photoanode improves the water oxidation performance further, with a 211 % enhancement in Jph at 1.23 VRHE and a 0.21 V cathodic shift in onset potential. Thin layers of NiOOH and FeNiOOH co-catalysts exhibit 100 and 155 % enhancement in Jph, respectively. Characterization and electrochemical measurements reveal that the enhanced performance is a result of reduced bulk recombination by temperature driven In/Sn substrate impurity doping and improved surface oxidation kinetics by the metal oxy-hydroxide overlayer. Especially deposition of FeOOH onto In/Sn co-doped α-Fe2O3 significantly reduces resistance at the semiconductor/electrolyte interface, leading to the shift in onset potential. Further, the results indicate that all the samples exhibit a quantitative correlation between the cathodic shift in photocurrent onset potential (Vonset) and flat band potential (Vfb).

Författare

Aadesh P. Singh

Chalmers, Fysik, Kemisk fysik

Alexander Levinsson

Chalmers, Fysik, Kemisk fysik

Beniamino Iandolo

Chalmers, Fysik, Kemisk fysik

Jani Oksanen

Aalto-Yliopisto

Anders Hellman

Chalmers, Fysik, Kemisk fysik

Björn Wickman

Chalmers, Fysik, Kemisk fysik

Journal of Photochemistry and Photobiology A: Chemistry

1010-6030 (ISSN)

Vol. 401 112781-

Drivkrafter

Hållbar utveckling

Styrkeområden

Nanovetenskap och nanoteknik (SO 2010-2017, EI 2018-)

Transport

Energi

Materialvetenskap

Ämneskategorier

Fysikalisk kemi

Atom- och molekylfysik och optik

Teoretisk kemi

Infrastruktur

Chalmers materialanalyslaboratorium

Nanotekniklaboratoriet

DOI

10.1016/j.jphotochem.2020.112781

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Senast uppdaterat

2020-08-30