Modulation of Photogenerated Carrier Transport by Integration of Sb₂O₃ with Fe₂O₃ for Improved Photoelectrochemical Water Oxidation

Abstract

Optimization of photogenerated carrier transport by heterojunction engineering has been realized as an effective strategy to improve the electrode performance in photoelectrochemical (PEC) systems. We report for the first time a type II heterostructure consisting of Sb2O3 and Fe2O3 for significantly enhanced PEC water oxidation. The as-fabricated photoanode exhibits prominent performance with a photocurrent density as high as 1.31 mA cm–2 at 1.23 V (vs. reversible hydrogen electrode), 14.5 times that of bare Fe2O3, as well as remarkable applied bias photon-to-current efficiency (10.7 times that of Fe2O3) and long-term stability (over 20 h). Notably, it outperforms all the Sb2O3-based photoanodes reported to date. The excellent PEC performance is ascribed to the rational integration of the matched merits of different components, i.e., interleaved step energy bands and complementary band gaps of Sb2O3 and Fe2O3. Along with the enhanced electrical conductivity, the photogenerated carriers are capable of flowing to the desired direction at a fast migration rate for participating in redox reactions on the electrode surface, and the electron–hole recombination is simultaneously efficiently inhibited.

Nano multi-layered HfO2/α-Fe2O3 nanocomposite photoelectrodes for photoelectrochemical water splitting

“…The donor density of the HfO 2 /α - Fe 2 O 3 film is about 1.95 × 10 20 cm −3 , which is almost 2 times higher than that of α - Fe 2 O 3 film (about 1.15 × 10 20 cm −3 ). This finding demonstrated that the heterojunction successfully increased the PEC performance by increasing conductivity, facilitating the fast transfer of photogenerated carriers, and increasing the degree of semiconductor energy band bending [ 73 ].…”

Metal–organic Framework-Derived CoSx/NiS Co-Decorated Heterostructures: Toward Simultaneous Acceleration of Charge Carrier Separation and Catalytic Kinetics

“…High-efficiency solar-to-hydrogen production has attracted promising attention due to its clean and carbon-neutral characteristics, which provides a pathway to overcoming the global energy crisis and environmental issues. , Thereinto, photoelectrochemical (PEC) water splitting is convincing as an intriguing avenue for hydrogen production from abundant solar energy and water with high purity. − However, the sluggish kinetics of the water oxidation process, derived from the complicated four-electron transfer pathway, seriously impede the development in practical applications. − TiO 2 is one of the most promising semiconductor photoanodes due to its favorable valence-band position, high activity, and robust stability. Nevertheless, bare TiO 2 undergoes intrinsic drawbacks such as a large bandgap, high recombination rate, and slow kinetics of oxygen evolution. , Designing and engineering excellent photoanodes, simultaneously possessing high charge carrier separation, wide absorption range, and water oxidation kinetics, still face great challenges. , …”

“…12,13 Designing and engineering excellent photoanodes, simultaneously possessing high charge carrier separation, wide absorption range, and water oxidation kinetics, still face great challenges. 14,15 To improve the PEC performance, several approaches have been adopted and developed, such as heterostructure construction, elemental doping, cocatalyst modification, or surface state passivation. 16−18 Heterostructure construction by coupling semiconductors with small bandgaps is a promising pathway to improve light utilization and electron−hole separation.…”