On the Limits of Photocatalytic Water Splitting

The major drawbacks on the limited H2 and O2 evolution activities of one-step photocatalytic water splitting systems are given here with the emphasis on charge recombination, back-oxidation reactions, and mass transfer limitations. Suppression of these unwanted phenomena is shown to be possible with the usage of small crystal-sized photocatalysts with low defect concentrations, presence of phase junctions, selection of co-catalyst that would be active for H2 evolution but inactive for O2 reduction, coating of the co-catalyst or the whole photocatalyst with selectively permeable nanolayers, and usage of photocatalytic systems with high solid–liquid and liquid–gas surface areas. The mass transfer limitations are shown to be important especially in the liquid–gas interfaces for agitated and suspended systems with estimated H2 transfer rates in the range of ∼200–8000 μmol/h.


The biocatalytic effect of Halobacterium halobium on photoelectrochemical hydrogen production
Sediroglu, V; Eroglu, I; Yucel, M; Turker, L; Gündüz, Ufuk (1999-04-30)
Hydrogen gas can be produced electrochemically by leading a current through two electrodes immersed in a NaCl solution. Bacteriorhodopsin (BR) a protein found in the purple membrane of Halobacterium halobium, is known to pump protons across the membrane upon illumination. In this study, the effect of BR on photoelectrochemical hydrogen production was investigated. A batch type bio-photoelectrochemical reactor was designed and constructed. The photoelectrochemical hydrogen production experiments were perform...
On the Electrochemical Reduction Mechanism of CaWO4 to W Powder
Erdogan, Metehan; Karakaya, İshak (2012-08-01)
The reduction mechanism of CaWO4 to W in molten eutectic CaCl2-NaCl electrolyte has been studied. Cyclic voltammetry and constant potential electrolysis tests were performed to determine the reversible cell potential. Analyses of the experimental results revealed that at least 2.2 V was required to compensate the potentials for the accompanying cell reaction and the electrode polarizations. A cell reaction was proposed by associating the experimental results and the Gibbs energy changes of the possible reac...
Development of activated carbon/bimetallic transition metal phosphide composite materials for electrochemical capacitors and oxygen evolution reaction catalysis
Köse, Kadir Özgün; Aydınol, Mehmet Kadri (2022-09-01)
Pinecone-derived activated carbon (AC) and bimetallic transition metal phosphide (TMP) composites were produced and utilized as electrochemical capacitor (EC) electrodes and oxygen evolution reaction (OER) catalysts in this study. The base transition metal (TM) was Ni for all samples, and the secondary TM was one of Fe, Mn and Co. AC serves as a porous structure for double layer formation and active sites for OER catalysis. Bimetallic TMP is utilized due to redox reactions in EC and catalytic activity in OE...
The structural and electronic properties of BN and BP compounds and BNxP1-x alloys
Mohammad, Rezek; Katırcıoğlu, Şenay (Elsevier BV, 2009-06-10)
The structural and electronic properties of BN and BP compounds and BNxP1-x alloys have been investigated by full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). The total energies and electronic band structures of these compounds have been calculated for different approximations of exchange-correlation energy. The comparative study has showed that the Perdew-Wang-generalized gradient approximation (PW-GGA) is the best one to produce the measured structur...
On the mechanism of photocatalytic CO2 reduction with water in the gas phase
Üner, Deniz (2012-02-12)
The mechanism of photocatalytic reduction of CO2 with H2O over Pt-TiO2 films produced by the sol-gel deposition over glass beads was investigated. The accumulation of significant amount of carbonaceous intermediate on the surface followed by deactivation indicated the rate limiting reaction is the water splitting reaction, similar to the natural photosynthetic systems. When gas phase hydrogen was allowed in the system, the carbonaceous intermediates were converted to methane at rates higher than the artific...
Citation Formats
B. İpek Torun and D. Üner, On the Limits of Photocatalytic Water Splitting. 2019, p. 1.