Cocatalysts for Photocatalytic Overall Water Splitting

Knowing that the Rh Cr Oj cocatalyst functions as an evolution site, the role of 

TABLE 11.2 Rates of gas evolution for overall water splitting using GaN ZnO photocatalyst modified with various cocatalysts with and without co-loading of Cr under UV irradiation (A 300nm)  

Cocatalyst Loading amount (wt %) Rate of evolution ( jmol h ) Cr co-loading amount (wt %) Rate of evolution ( jmol h )  

TABLE 11.3 Rate of gas evolution using Rh Cr Oj- or RuO -loaded GaNtZnO in the presence of sacrificial reagents under visible-light irradiation (A 400nm)° 

Pt and Rh, catalyze the back reaction from and to H O. This back reaction occurs at very high rates, even without iUumination (dark reaction) [64], This was considered to be a general problan to be overcome for overall water splitting [59]. Co-loading Cr with another transition metal drastically improved the and evolution rates [61] and coated the metal surfaces with a nanoscale metal core Cr shell structure. It clearly suppresses the back reaction [64]. Yoshida et al. performed electrochemical and spectroscopic investigations on a model Pt or Rh electrode covered with an approximately 2-nm-thick Cr layer, which corresponds to the Cr layer of nanoparticles on photocatalysts [65]. The electrochemical method revealed that the Cr-coated electrode still exhibited proton adsorption and desorption peaks in cyclic voltammograms and did 

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Iwase H, Kato H, Kudo A (2006) Nanosized gold particles as an efficient cocatalyst for photocatalytic overall water splitting. Catal Lett 108 6-9... 

Unique Property of Rh2-yCryO3 Cocatalyst for Photocatalytic Overall Water Splitting... 

Our group has previously reported that the photocatalytic activity of Ni-loaded K2La2Ti30io for overall water splitting is improved by coloading with Cr, while modification with Cr alone did not result in appreciable evolution of H2 or O2 [47]. This result suggests that the increase in activity is attributable to interaction between Ni and Cr in the cocatalyst, motivating further investigation of Cr as a cocatalyst in combination with other transition metals [13-16]. 

Table 10.4 Photocatalytic activities of various cocatalyst chromium-loaded (Ga, jjZrij )(N,, jOjj) combinations for overall splitting of water under UV irradiation A > 300 nm).

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