Efficient Water Splitting Cascade Photoanodes with Ligand‐Engineered MnO Cocatalysts

Abstract

The band edge positions of semiconductors determine functionality in solar water splitting. While ligand exchange is known to enable modification of the band structure, its crucial role in water splitting efficiency is not yet fully understood. Here, ligand‐engineered manganese oxide cocatalyst nanoparticles (MnO NPs) on bismuth vanadate (BiVO4) anodes are first demonstrated, and a remarkably enhanced photocurrent density of 6.25 mA cm−2 is achieved. It is close to 85% of the theoretical photocurrent density (≈7.5 mA cm−2) of BiVO4. Improved photoactivity is closely related to the substantial shifts in band edge energies that originate from both the induced dipole at the ligand/MnO interface and the intrinsic dipole of the ligand. Combined spectroscopic analysis and electrochemical study reveal the clear relationship between the surface modification and the band edge positions for water oxidation. The proposed concept has considerable potential to explore new, efficient solar water splitting systems.

Reduced graphene oxide‐based materials for electrochemical energy conversion reactions

“…Recently, substantial research have been conducted on developing earth‐abundant element based electrocatalysts with high activity, selectivity, and long‐term stability. Transition metals and their compounds, such as transition metal oxides, hydroxides, chalcogenides, phosphides, carbides, and borides, have been intensively investigated as a substitute of noble metal catalysts. Albeit tremendous effort and attention, the performance of these electrocatalysts for energy conversion is still unsatisfactory compared to noble‐metal–catalysts.…”

Crystal Facet Engineering of TiO2 Nanostructures for Enhancing Photoelectrochemical Water Splitting with BiVO4 Nanodots

“…BiVO 4 was electrodeposited onto the two types of TiO 2 nanostructures using previously reported methods [ 5 , 23 ]. A precursor was prepared by dissolving bismuth nitrate pentahydrate (BiN 3 O 9 , 98%, Junsei) in a solution of vanadium oxide sulfate hydrate (VOSO 4 , 99.99%, Aldrich) at pH < 0.5 with nitric acid (HNO 3 , 67%, Junsei).…”

Understanding Surface Modulation to Improve the Photo/Electrocatalysts for Water Oxidation/Reduction

“…In addition, the metal oxide MnO catalysts on BiVO 4 /WO 3 functionalized with BF 4 − oxidizes water molecules under neutral condition, showed the enhanced catalytic performance. This result is due to the band edge modulation created by ligand functionalization on the surface [80]. The barrier height at the solid-liquid interface, which is measured as open-circuit voltage, can be controlled by the surface functionalities [73,81].…”