Search

A photocharge/discharge strategy is proposed to initiate the WO3 photoelectrode and suppress the main charge recombination, which remarkably improves the photoelectrochemical (PEC) performance. The photocharged WO3 surrounded by a 8–10 nm overlayer and oxygen vacancies could be operated more than 25 cycles with 50 h durability without significant decay on PEC activity. A photocharged WO3/CuO photoanode exhibits an outstanding photocurrent of 3.2 mA cm−2 at 1.23 VRHE with a low onset potential of 0.6 VRHE, which is one of the best performances of p‐n heterojunction structure. Using nonadiabatic molecular dynamics combined with time‐domain DFT, we clarify the prolonged charge carrier lifetime of photocharged WO3, as well as how electronic systems of photocharged WO3/CuO semiconductors enable the effective photoinduced electrons transfer from WO3 into CuO. This work provides a feasible route to address excessive defects existed in photoelectrodes without causing extra recombination. [ABSTRACT FROM AUTHOR]

Owing to the sluggish kinetics suppressing the oxygen evolution reaction, developing single atoms (SAs) catalyst oxygen evolution reaction catalysts on photoelectrodes is challenging for accelerating charge separation and transfer on photoelectrochemical water splitting. Herein, we elaborately demonstrate the decoration of platinum SAs on hybrid crystalline/amorphous CoFe LDH, and assess the role of SAs on the photogenerated charge carrier separation and transport of photoelectrode. The crystalline/amorphous CoFe LDH is capable of embedding the platinum SAs in its structure by modulating the electronic structure. The single atoms platinum in catalyst enables the effective charge transfer and suppress the charge recombination of the BiVO 4 photoelectrode. The SAs Pt/AC-CoFe catalyst delivers an overpotential of 230 mV at 10 mA cm−2, obviously lower than those of AC-CoFe without the introduction of SAs Pt. The SAs Pt/AC-CoFe/BiVO 4 exhibits an excellent PEC performance, a current density of 5.14 mA cm−1 obtained at 1.23 V RHE in 1 M KBi under one sun illumination with a stability of 20 h. This work proposes a rational design of single atoms catalysts decorated on semiconductors and reveals the potential of the single atoms to boost charge carrier kinetics. [Display omitted] • The synthesis of single atom doping engineering for photoelectrocatalysis research. • Atomic Pt-O coordination in CoFe LDH leads to the enhanced charge carrier transport of semiconductor. • Report on single atomic Pt and amorphous-crystalline (AC) hybride structure suppresses the charge recombination of BiVO 4. • SAs Pt/AC-CoFe/BVO achieves a current density of 5.14 mA cm-1 at 1.23 V RHE with 20 h stability. • A significant conceptual advance to the catalysis community on pushing the single atom doping engineering on PEC water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • Gradient Ce doping on Fe 2 O 3 with the construction of built-in electric field. • Surface polarization on gradient Ce doped Fe 2 O 3 reduced the interfacial oxygen vacancies. • The photoanode exhibited a photocurrent of 2.50 mA cm−2 at 1.50 V RHE with a low onset potential of 0.64 V RHE. • DFT calculations demonstrated the elimination of deep trap state and the reduction of charge recombination. Photoelectrochemical (PEC) water splitting is one of the most strategies for solar energy storage and utilization. Hematite as one of the promising candidates for PEC research, has a short hole diffusion length and short carrier lifetime, resulting in PEC conversion efficiency far below the theoretical value. In this work, a facile but efficient strategy was introduced for the growth of gradient Ce doped hematite nanorods, following with the sequent photoactivation process. The gradient Ce doping not only increased the conductivity of bulk material, but also importantly, constructed a built-in electric field by the addition of Ce element, which remarkably enhanced the charge separation and transfer from the bulk to the surface. Moreover, the surface polarization under illumination was applied for the reduction of overpotential and the enhancement of photocurrent density, taking a role of cocatalyst decoration. It reduced the oxygen vacancies concentration at the surface, which further reduced the surface recombination owing to the passivation from photoactivation. According to these, the resulting photoanode exhibited a photocurrent of 1.92 and 2.50 mA cm−2 at 1.23 and 1.50 V RHE , respectively, with onset potential of 0.64 V RHE under AM 1.5G illumination. This work opens a useful strategy of modifying the electronic structure and constructing the interface structure for improving PEC performance on hematite-based photoelectrodes for solar energy storage and utilization. [ABSTRACT FROM AUTHOR]

• Environmentally friendly urea induced Ni,Fe-based hydroxides as robust OEC, replacing complex organic materials. • Urea as nitrogen/carbon source facilitates the growth of OEC layer and passivates the surface state of BiVO 4. • A long-term stability of 40 h at 0.8 V RHE is obtained for urea induced NiFeOOH/BiVO 4. • Using cheap and non-precious metal-based electrocatalysts overcomes the bottle-necks of PEC water splitting stability. Stability is one of essential factors for evaluating the photoelectrochemical (PEC) water splitting performance on photocorroded semiconductors for practical applications. Cocatalyst decoration can only maintain the stability for several hours, and organic/inorganic hybrid photoelectrodes (e.g. polymer coated photoelectrodes) also has a limited durability. Therefore, it is challenging to develop a facile but effective approach for stabilizing the photoelectrodes. In this work, we induced a handful of cheap urea into the Ni,Fe-based hydroxides as robust and conformal OECs layers, deposited on the BiVO 4 photoanodes by an one-step impregnation process. Urea, an assisted nitrogen/carbon source, played an active role on the uniform growth of ultrathin OEC layer, replacing the complex organic cocatalyst. The thickness of urea induced Ni,Fe-based OEC could be modified by tuning the amount of urea, thereby improving the carrier dynamics and protecting photoelectrodes from photocorrosion. The presence of urea facilitates to deposit a homogeneous cocatalyst layer with higher electron transfer than the absence of urea, resulting in a high electrocatalytic OER and PEC performance. The optimized urea-NiFeOOH/BiVO 4 photoanode showed a photocurrent density of 4.8 mA cm−2 at 1.23 V RHE with impressive stability over 40 h at a potential of 0.8 V RHE , which is one of the best PEC stabilities using NiFe-based OECs on BiVO 4. Benefiting from the strong coordination bond between the metal ions and urea, the C and N elements remained stable in the OEC layer before and after PEC test. This work presents a potential application using cheap, non-precious metal based electrocatalysts to overcome the bottle-necks limiting a long-term stability of PEC water splitting. [ABSTRACT FROM AUTHOR]