A Water‐Splitting System with a Cobalt (II,III) Oxide Co‐Catalyst‐Loaded Bismuth Vanadate Photoanode Along with an Organo‐Photocathode

Abstract

In the water‐splitting reaction, the oxidation of water to O2 is considered to be a kinetically demanding process, so that a co‐catalyst has been usually applied to promote water oxidation. This work demonstrates that, when loading mixed‐valence cobalt (II,III) oxide (Co3O4) dispersed in a Nafion membrane (Nf) on a nanoporous bismuth vanadate (BiVO4) photoanode (i. e., BiVO4/Nf[Co3O4]), stable and efficient water oxidation occurred. In particular, it is noteworthy that the BiVO4/Nf[Co3O4] photoanode exhibited stable performance even in an acidic medium (pH=2). In the present system consisting of a BiVO4/Nf[Co3O4] photoanode along with an organo‐photocathode, the stoichiometric formation of O2 and H2 successfully occurred by applying just 0.1 V between the photoelectrodes (cf. maximum efficiency, ca. 0.2 %), which was superior to the prototype comprising BiVO4 and Pt counter electrode. The Co3O4 loading can effectively suppress the collapse of the nanostructured BiVO4 upon photocorrosion, resulting in the stable and kinetically efficient consumption of holes in BiVO4.

Selective Valorization of Glycerol to Formic Acid on a BiVO4 Photoanode through NiFe Phenolic Networks

“…The efficient kinetics give the GOR a clear advantage in achieving high photocurrents on BVO-based photoanodes in acidic conditions compared to that of the OER. As reported by a previous work, BVO displayed a low photocurrent of about 0.9 mA•cm −2 at 1.2 V versus RHE (pH = 2) with an onset potential of 0.7 V versus RHE for OER, 51 corresponding to our investigation (Figure 2b). The onset potential for the GOR is about 300 mV lower than that for the OER on BVO, indicating the favorable kinetics of the GOR in acidic conditions.…”

Porphyrins and phthalocyanines as biomimetic tools for photocatalytic H2production and CO2reduction

“…The same research group reported in 2020 a photoelectrochemical water-splitting system based on the same Pt loaded ZnPc/C60 bilayer photocathode but using a photoanode comprised with a mixed-valence cobalt( ii , iii ) oxide (Co 3 O 4 ) disperse in a Nafion membrane on a nanoporous BiVO 4 . 315 The stoichiometric generation of H 2 and O 2 occurred by applying a bias voltage as low as 0.1 V, which was superior to the reference system comprising BiVO 4 and Pt, ant the light-to-hydrogen conversion efficiency was ca. 0.08% at 0.6 V. The presence of a cobalt cocatalyst not only improved the water oxidation process but also the stability of the device even in an acidic medium.…”

Development of dual-functional catalysis for hydrazine oxidation by an organic p–n bilayer through in situ formation of a silver co-catalyst

“… 16–20 We have been studying organic p–n bilayer, including p-type and n-type, semiconductors for application in photoelectrochemical and photocatalytic reactions in the water phase. 21–32 Some unique reactions, which had not been induced so far by conventional photocatalysts, were also found to occur. 27–32 In our studies, an organic p–n bilayer using 3,4,9,10-perylenetetracarboxylic-bis-benzimidazole (PTCBI) and cobalt phthalocyanine (CoPc) as n-type and p-type semiconductors, respectively, achieved the catalytic oxidation of thiol under illumination and in the dark.…”