Abstract
Rational design of the catalysts is impressive for sustainable energy conversion. However, there is a grand challenge to engineer active sites at the interface. Herein, hierarchical ...transition bimetal oxides/sulfides heterostructure arrays interacting two-dimensional MoO
x
/MoS
2
nanosheets attached to one-dimensional NiO
x
/Ni
3
S
2
nanorods were fabricated by oxidation/hydrogenation-induced surface reconfiguration strategy. The NiMoO
x
/NiMoS heterostructure array exhibits the overpotentials of 38 mV for hydrogen evolution and 186 mV for oxygen evolution at 10 mA cm
−2
, even surviving at a large current density of 500 mA cm
−2
with long-term stability. Due to optimized adsorption energies and accelerated water splitting kinetics by theory calculations, the assembled two-electrode cell delivers the industrially relevant current densities of 500 and 1000 mA cm
−2
at record low cell voltages of 1.60 and 1.66 V with excellent durability. This research provides a promising avenue to enhance the electrocatalytic performance of the catalysts by engineering interfacial active sites toward large-scale water splitting.
Abstract
Rational design of single atom catalyst is critical for efficient sustainable energy conversion. However, the atomic-level control of active sites is essential for electrocatalytic materials ...in alkaline electrolyte. Moreover, well-defined surface structures lead to in-depth understanding of catalytic mechanisms. Herein, we report a single-atomic-site ruthenium stabilized on defective nickel-iron layered double hydroxide nanosheets (Ru
1
/D-NiFe LDH). Under precise regulation of local coordination environments of catalytically active sites and the existence of the defects, Ru
1
/D-NiFe LDH delivers an ultralow overpotential of 18 mV at 10 mA cm
−2
for hydrogen evolution reaction, surpassing the commercial Pt/C catalyst. Density functional theory calculations reveal that Ru
1
/D-NiFe LDH optimizes the adsorption energies of intermediates for hydrogen evolution reaction and promotes the O–O coupling at a Ru–O active site for oxygen evolution reaction. The Ru
1
/D-NiFe LDH as an ideal model reveals superior water splitting performance with potential for the development of promising water-alkali electrocatalysts.
Rational design efficient transition metal-based electrocatalysts for oxygen evolution reaction (OER) is critical for water splitting. However, industrial water-alkali electrolysis requires large ...current densities at low overpotentials, always limited by intrinsic activity. Herein, we report hierarchical bimetal nitride/hydroxide (NiMoN/NiFe LDH) array as model catalyst, regulating the electronic states and tracking the relationship of structure-activity. As-activated NiMoN/NiFe LDH exhibits the industrially required current density of 1000 mA cm
at overpotential of 266 mV with 250 h stability for OER. Especially, in-situ electrochemical spectroscopic reveals that heterointerface facilitates dynamic structure evolution to optimize electronic structure. Operando electrochemical impedance spectroscopy implies accelerated OER kinetics and intermediate evolution due to fast charge transport. The OER mechanism is revealed by the combination of theoretical and experimental studies, indicating as-activated NiMoN/NiFe LDH follows lattice oxygen oxidation mechanism with accelerated kinetics. This work paves an avenue to develop efficient catalysts for industrial water electrolysis via tuning electronic states.
The photochemical conversion of carbon dioxide provides a straightforward and effective strategy for the highly efficient production of solar fuels with high solar‐light utilization efficiency. ...However, the high recombination rate of photoexcited electron–hole (e‐h) pairs and the poor photostability have greatly limited their practical applications. Herein, a practical strategy is proposed to facilitate the separation of e‐h pairs and enhance the photostability in a semiconductor by the use of a Schottky junction in a bimetal‐graphene‐semiconductor stack array. Importantly, Au‐Cu nanoalloys (ca. 3 nm) supported on a 3D ultrathin graphene shell encapsulating a p‐type Cu2O coaxial nanowire array promotes the stable photochemical reduction of CO2 to methanol by the synergetic catalytic effect of interfacial modulation and charge‐transfer channel design. This work provides a promising lead for the development of practical catalysts for sustainable fuel synthesis.
A copper–gold nanoalloy supported on a three‐dimensional ultrathin graphene shell encapsulating a p‐type Cu2O coaxial nanowire array promotes the stable photochemical reduction of CO2 to methanol by the synergetic catalytic effect of interfacial modulation and charge‐transfer channel design.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Photoelectrochemical (PEC) solar water splitting over oxynitrides is a promising process for renewable hydrogen production. However, the oxynitride heterojunction photoanodes with high ...charge-separation efficiency and stability, which have unique dimensionality-dependent integrative and synergic effects, are intriguing but still underdeveloped. Here, we design and fabricate the 1D/2D nanorod/nanosheet-assembled tantalum oxynitride (TaON) photoanode with the high PEC activity. Especially, integrated 3D heterojunction photoanodes comprising the 1D/2D barium-doped TaON (Ba-TaON) array and 2D carbon nitride (C sub(3)N sub(4)) nanosheets decorated with CoO sub(x) nanoparticles as a novel stack design were firstly prepared and the 3D CoO sub(x)/C sub(3)N sub(4)/Ba-TaON photoanodes with the remarkable photostability reached the pronounced photocurrent of 4.57 mA cm super(-2) at 1.23 V vs. RHE under AM 1.5G simulated sunlight. More broadly, the harness charge transfer process of this unique 3D heterojunction photoanode with the intrinsic requirements has been identified by the quantitative analysis combined with the electrochemical impedance and photoluminescence analysis. All the results highlight the great significance of the 3D dimensionality-dependent heterojunction as a promising photoelectrode model for the application in solar conversion. The cooperating amplification effects of nanoengineering from composition regulation, morphology innovation and heterojunction construction provide a valuable insight for creating more purpose-designed (oxy)nitride photoelectrodes with highly efficient performance.
When Alpha met Beta: A tunable α–β surface phase junction on Bi2O3 can significantly improve photocatalytic degradation of RhB and MO solution over individual α-Bi2O3 or β-Bi2O3 surface phases. This ...enhanced photocatalytic performance is mainly attributed to the efficient charge separation and transfer across the α–β phase junction.
•α-/β-Bi2O3 heterojunction were prepared via in situ hydrothermal process.•Phase and morphology transformation were obtained for Bi2O3nanostructures.•Exceptional photocatalytic performance of α-/β-Bi2O3 heterojunction were obtained.•Mechanism for charge separation and transfer across α–β phase junction was proposed.
Visible-light-responsive α–β phase heterojunction on Bi2O3 nanowire photocatalysts were prepared via a facile in situ hydrothermal process in assistance with the post-heat treatment route. The as-prepared samples were characterized by X-ray diffraction (XRD), electron microscope (EM), Brunauer–Emmett–Teller analysis (BET), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance absorption spectra (UV–vis). XRD patterns revealed that the α–β phase heterojunction over Bi2O3 composites with the monoclinic α-Bi2O3 and the tetragonal β-Bi2O3 structure were obtained and the relative ratios between α-Bi2O3 and β-Bi2O3 can readily be tailored by the control of the reaction temperature. Within the hydrothermal temperature range, the morphology of as-prepared samples transformed progressively from two-dimensional β-Bi2O3 sheets to the α-/β-Bi2O3 nanowires junction. The exceptional photocatalytic performance of α-/β-Bi2O3 heterojunction for the degradation of cationic rhodamine B and anionic methyl orange under visible-light irradiation is superior over that of β-Bi2O3 sheets, which is ascribed to the efficient charge separation and transfer across the α-β phase junction. The phase-junction approach will open new avenues for the development of efficient photocatalysts for environmental remediation and energy conversion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The fundamental catalytic limitations for the photoreduction of CO2 still remain: low efficiency, poor charge transport and short lifetime of catalysts. To address the critical challenges, an ...efficient strategy based on spatial location engineering of phosphate (PO4) and oxygen-vacancy (Vo) confined in Bi2WO6 (BWO) atomic layers is employed to establish and explore an intimate functional link between the electronic structures and activities of Vo-PO4-BWO layers. Both theoretical and experimental results reveal, the Vo-PO4-BWO layers not only narrow the band gap from the UV to visible-light region but also reduce the resistance. The time-resolved photoluminescence decay spectra exhibit the increasing carrier lifetime for Vo-PO4-BWO layers, indicating the improved charge separation and transfer efficiency. As expected, the Vo-PO4-BWO layers with the simultaneously efficient light absorption and charge transport properties achieve much higher methanol formation rate of 157 μmol g-1 h-1, over 2 and 262 times larger than that of BWO atomic layers and bulk BWO. This work may reveal that the light absorption and spatial charge transport over atomic layers could benefit CO2 conversion and shed light on the design principles of efficient photocatalysts towards solar conversion applications.
Simultaneously efficient light absorption and charge transport in phosphate and oxygen-vacancy confined in bismuth tungstate atomic layers have been achieved for excellent visible-light-driven CO2 reduction. Display omitted
•Phosphate and oxygen-vacancy confined in BWO atomic layers were achieved•Vo-PO4-BWO atomic layers exhibit efficient light absorption and charge transport•Vo-PO4-BWO layers present highest methanol formation by CO2 photoreduction•Mechanism of CO2 photoreduction over Vo-PO4-BWO atomic layers is proposed
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Developing robust water splitting photocatalyst remains a pivot challenge for solar-to-fuel conversion. Herein, two-dimensional (2D) Janus bilayer heterostructures are reported by ...sulfur-vacancy-confined-in ZnIn2S4 (Vs-ZnIn2S4) and WO3 nanosheets as an all-solid-state Z-scheme prototype. First-principle calculations and experimental observations clearly confirm the spontaneous formation of this redox-mediator-free Z-scheme van der Waals heterostructure at atomic level, not only facilitating the space separation of photoexcited carriers with high charge density, enhancing charge dynamics and optimizing charge lifetime, but also accumulating electrons in conduction band of Vs-ZnIn2S4 and holes in valence band of WO3 by internal electric field through W–S bonds. After integrated by NiS quantum dots, novel 2D/2D NiS/Vs-ZnIn2S4/WO3 heterostructures with high stability exhibited an outstanding visible-light hydrogen evolution rate of 11.09 mmol g−1 h−1 and an apparent quantum efficiency about 72% at 420 nm, the highest value so far reported among the family of ZnIn2S4 photocatalysts. This work not only presents novel Janus heterostructures but also paves the atomic-level structural and interfacial design and the construction of 2D Janus bilayer Z-scheme heterojunctions for solar energy conversion applications.
The redox-mediator-free Z-scheme Janus bilayer Vs-ZnIn2S4/WO3 heterostructures have been achieved for excellent visible-light-driven hydrogen evolution. Display omitted
•2D Janus bilayer Vs-ZnIn2S4/WO3 heterostructures were achieved.•Z-scheme heterostructures promote atomic-level charge transport and separation.•NiS/Vs-ZnIn2S4/WO3 heterostructures achieve highest hydrogen evolution rate.•Z-scheme mechanism via DTF calculations and experimental observations is proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Photoelectrochemical (PEC) water splitting is recognized as a sustainable strategy for hydrogen generation due to its abundant hydrogen source, utilization of inexhaustible solar energy, high‐purity ...product, and environment‐friendly process. To actualize a practical PEC water splitting, it is paramount to develop efficient, stable, safe, and low‐cost photoelectrode materials. Recently, graphitic carbon nitride (g‐C3N4) has aroused a great interest in the new generation photoelectrode materials because of its unique features, such as suitable band structure for water splitting, a certain range of visible light absorption, nontoxicity, and good stability. Some inherent defects of g‐C3N4, however, seriously impair further improvement on PEC performance, including low electronic conductivity, high recombination rate of photogenerated charges, and limited visible light absorption at long wavelength range. Construction of g‐C3N4‐based nanosized heteroarrays as photoelectrodes has been regarded as a promising strategy to circumvent these inherent limitations and achieve the high‐performance PEC water splitting due to the accelerated exciton separation and the reduced combination of photogenerated electrons/holes. Herein, we summarize in detail the latest progress of g‐C3N4‐based nanosized heteroarrays in PEC water‐splitting photoelectrodes. Firstly, the unique advantages of this type of photoelectrodes, including the highly ordered nanoarray architectures and the heterojunctions, are highlighted. Then, different g‐C3N4‐based nanosized heteroarrays are comprehensively discussed, in terms of their fabrication methods, PEC capacities, and mechanisms, etc. To conclude, the key challenges and possible solutions for future development on g‐C3N4‐based nanosized heteroarray photoelectrodes are discussed.
Constructing graphitic carbon nitride (g‐C3N4)‐based heteroarrays as photoelectrodes has been regarded as the most straightforward and efficient strategy for enhancing the photoelectrochemical (PEC) performance of g‐C3N4. On the one hand, heterojunctions between g‐C3N4 and the secondary material can accelerate the separation of photogenerated electrons/holes. On the other hand, highly‐ordered array architectures provide the fast transport routes for photogenerated carriers, thus significantly suppressing the recombination of photo‐induced charges. Briefly, g‐C3N4‐based heteroarrays will play a key role in the next years, and will help to pave an avenue to achieve the efficient and stable PEC water splitting for sustainable solar‐driven hydrogen production.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A three-dimensional (3D) multicomponent oxide, Bi₁₂TiO₂₀/TiO₂ hierarchical heterostructure was successfully synthesized via a one-step and template-free hydrothermal route. X-ray diffraction and ...X-ray photoelectron spectroscopy measurements confirm that the composition of the as-fabricated sample is Bi₁₂TiO₂₀/TiO₂ composite. Scanning and transmission electron microscopy observation reveals that the as-synthesized sample is microsized flower-like hierarchical networks consisted of Bi₁₂TiO₂₀ nanorods decorated with the primary TiO₂ nanoparticles. Extension of the light absorption from the ultraviolet region to the visible-light region was confirmed by UV–vis absorption spectra. Due to the structure–property relationships, the 3D Bi₁₂TiO₂₀/TiO₂ heterostructure exhibited enhanced visible photocatalytic activity over that of Bi₁₂TiO₂₀ and TiO₂ samples in the decomposition of Rhodamine B in water which is a typical model pollutant. The enhanced photocatalytic activity can be attributed to the extended absorption in the visible light region resulting from the 3D Bi₁₂TiO₂₀/TiO₂ heterostructures, and the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the Bi₁₂TiO₂₀/TiO₂ junction interface, demonstrating that the Bi₁₂TiO₂₀/TiO₂ heterostructure is a promising candidate as a visible light photocatalyst.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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