Site-Selective Deposition of a Cobalt Cocatalyst onto a Plasmonic Au/TiO₂ Photoanode for Improved Water Oxidation

Abstract

Plasmonic Au/TiO2 thin film works as a stable water oxidation photoanode. Here we show that site-selective deposition of nanosized CoO x as a water oxidation cocatalyst at the edge of Au nanoparticles on the TiO2 film improves the photoelectrochemical water oxidation activity. The nanosized CoO x was deposited by a photoassisted electrochemical method onto the Au/TiO2 thin film. The CoO x loading amount was controllable by changing the amount of electric charge that flowed during the deposition, which influenced the photoelectrochemical performance. Under visible light, the optimized CoO x /Au/TiO2 thin film generated stable photoanodic current, which was ∼3 times higher than that obtained using Au/TiO2.

Rational design for gold nanoparticle-based plasmonic catalysts and electrodes for water oxidation towards artificial photosynthesis

“…Au@//Pb NP-incorporated mesoporous TiO 2 (Au@//Pb/ Misawa, Maeda, and co-workers selectively deposited CoO x at the periphery of Au NPs (d Au < 50 nm) on a TiO 2 electrode (CoO x /Au/TiO 2 ) as an electrocatalyst for OER by a PEC method. 62 The surface modification of the Au/TiO 2 electrode with an optimum loading amount of CoO x increased the selectivity for OER and the IPCE from 0.25% to 0.75% (ϕ OER ↑). Further, a solar-to-hydrogen efficiency of 0.052% was achieved under optimal conditions.…”

Extraterrestrial artificial photosynthetic materials for in-situ resource utilization

“…The valence band of an n-type semiconductor bends upward at the semiconductor/solution interface, allowing photo-generated holes to transfer to the electrolyte for O 2 evolution. The main photoanode materials are TiO 2 , Fe 2 O 3 , WO 3 , ZnO, BiVO 4 , Ta 3 N 5 and n-Si [ 3 , 61 – 66 ].…”

“…Therefore, photoanode materials with high activity and stability are indispensable in improving the energy conversion efficiency of PEC systems for EAP. Numerous n-type semiconductors have been exploited and investigated, including n-type silicon [ 66 ], oxides [ 61 – 64 ], nitrides [ 103 ] and sulfides [ 104 ], as photoanodes for O 2 production. In addition, finely dispersed cocatalyst nanoparticles (e.g.…”

“…In addition, finely dispersed cocatalyst nanoparticles (e.g. Co [ 61 ], Fe [ 66 ]), phosphides [ 105 ] and hydroxyapatite [ 106 ], or conformal thin layers of cocatalysts (e.g. oxyhydroxide, sulfides) [ 107 ] on the photoanode surface are also an effective approach for remarkable O 2 generation.…”

“…oxyhydroxide, sulfides) [ 107 ] on the photoanode surface are also an effective approach for remarkable O 2 generation. Among the diverse catalysts, TiO 2 , WO 3 , Fe 2 O 3 and BiVO 4 with befitting band structure and plummy stability of aqueous solution, are good n-type semiconductor photoanode materials for O 2 production through water oxidation [ 3 , 61 – 63 ]. At present, the O 2 production of unmodified individual photoanode materials still needs to be improved, mainly due to poor surface reaction kinetics and weak carrier separation and transport.…”