Highly Efficient Water Oxidation Photoanode Made of Surface Modified LaTiO2N Particles

An improved variation of highly active/durable O2‐evolving LaTiO2N powder‐based photoelectrode has been fabricated by pre‐cleaning the powder with mild polysulfonic acid and by homogeneous deposition of CoOx co‐catalyst aided by microwave annealing. The treatment in aqueous solution of poly(4‐styrene sulfonic acid) results in removal of surface LaTiO2N layers, forming fine pores in the crystallites. The CoOx co‐catalyst by microwave deposition in Co(NH3)6Cl3/ethylene glycol homogeneously covers the particle surface. The LaTiO2N powder is fabricated into particle‐transferred electrodes on Ti thin film supported on solid substrate. The modified LaTiO2N grains on the electrode serve as a highly active O2‐evolving photoanode achieving 8.9 mA cm−2 of the photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) in 0.1 m NaOH (pH 13) under solar‐simulator irradiation Airmass 1.5 Global (AM 1.5G). The activity has been much improved, compared with conventional LaTiO2N treated in mineral acid or with CoOx deposited by impregnation. The new electrode also exhibits better durability in fixed‐potential chronoamperometric tests under AM 1.5G irradiation. An improved variation of highly active/durable O2‐ evolving LaTiO2N powder‐based photoelectrode has been fabricated by pre‐cleaning the powder with mild polysulfonic acid and by homogeneous deposition of CoOx co‐catalyst aided by microwave annealing. Fabricated into particle‐transferred electrodes on Ti, the modified LaTiO2N serves as a highly active photoanode, achieving 8.9 mA cm−2 of the photocurrent density at 1.23 V versus RHE and longer active periods than those by previous methods.