Abstract
Interface engineering is a proven strategy to improve the efficiency of thin film semiconductor based solar energy conversion devices. Ta
3
N
5
thin film photoanode is a promising candidate ...for photoelectrochemical (PEC) water splitting. Yet, a concerted effort to engineer both the bottom and top interfaces of Ta
3
N
5
thin film photoanode is still lacking. Here, we employ n-type In:GaN and p-type Mg:GaN to modify the bottom and top interfaces of Ta
3
N
5
thin film photoanode, respectively. The obtained In:GaN/Ta
3
N
5
/Mg:GaN heterojunction photoanode shows enhanced bulk carrier separation capability and better injection efficiency at photoanode/electrolyte interface, which lead to a record-high applied bias photon-to-current efficiency of 3.46% for Ta
3
N
5
-based photoanode. Furthermore, the roles of the In:GaN and Mg:GaN layers are distinguished through mechanistic studies. While the In:GaN layer contributes mainly to the enhanced bulk charge separation efficiency, the Mg:GaN layer improves the surface charge inject efficiency. This work demonstrates the crucial role of proper interface engineering for thin film-based photoanode in achieving efficient PEC water splitting.
Two-dimensional Ruddlesden–Popper phase (2DRP) perovskites are known to exhibit improved photostability and environmental stability compared with their three-dimensional (3D) counterparts. However, ...fundamental questions remain over the interaction between the bulky alkylammoniums and the 2DRP perovskite framework. Here, we unambiguously demonstrate that a sulfur–sulfur interaction is present for a new bulky alkylammonium, 2-(methylthio)ethylamine hydrochloride (MTEACl). In addition to a weaker van der Waals interaction, the interaction between sulfur atoms in two MTEA molecules enables a (MTEA)2(MA)4Pb5I16 (n = 5) perovskite framework with enhanced charge transport and stabilization. The result is 2DRP perovskite solar cells with significantly improved efficiency and stability. Cells with a power conversion efficiency as high as 18.06% (17.8% certified) are achieved, along with moisture tolerance for up to 1,512 h (under 70% humidity conditions), thermal stability for 375 h (at 85 °C) and stability under continuous light stress (85% of the initial efficiency retained over 1,000 h of operation at the maximum power point).Two-dimensional perovskite solar cells have been engineered to be robust against moisture, high temperatures and light stress.
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FZAB, GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Fluorine‐anion surface engineering has now been used to activate catalytic active species, representing a completely new way of reconstruction toward oxygen evolution reaction (OER) active species. ...The electronegativity of the fluorine anion is the strongest so that it will be much easier to form weak metal–fluorine bonds with stronger ionicity, contributing to the dynamic migration of fluorine anions and finally enriching on the surface of both cobalt‐based oxide/oxyhydroxide. Surface enrichment of fluorine anions endows more hydrophilic surface character for accelerating the key process of oxygen‐related intermediate adsorption. Combining with an obviously improved electron transfer capacity, the F‐CoOOH/NF catalyst exhibits a greatly enhanced OER activity (270 mV at 10 mA cm−2) and reaction kinetics (54 mV dec−1) in alkaline medium. Surface anion engineering introduces a new concept for rational design advanced OER catalysts for energy conversion system.
Surface engineering by using fluoride ions was used to activate the catalytically active species of Co‐based materials. This is a completely new way of reconstruction toward OER‐active species. OER=oxygen evolution reaction; F green, Co purple.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Engineering electronic properties by elemental doping is a direct strategy to design efficient catalysts towards CO2 electroreduction. Atomically thin SnS2 nanosheets were modified by Ni doping for ...efficient electroreduction of CO2. The introduction of Ni into SnS2 nanosheets significantly enhanced the current density and Faradaic efficiency for carbonaceous product relative to pristine SnS2 nanosheets. When the Ni content was 5 atm %, the Ni‐doped SnS2 nanosheets achieved a remarkable Faradaic efficiency of 93 % for carbonaceous product with a current density of 19.6 mA cm−2 at −0.9 V vs. RHE. A mechanistic study revealed that the Ni doping gave rise to a defect level and lowered the work function of SnS2 nanosheets, resulting in the promoted CO2 activation and thus improved performance in CO2 electroreduction.
Nickel in thin tin: Atomically thin SnS2 nanosheets were modified by Ni doping for efficient electroreduction of CO2. Introduction of Ni into SnS2 nanosheets enhanced current density and Faradaic efficiency for carbonaceous product relative to pristine SnS2 nanosheets. When the Ni content was 5 at. %, Faradaic efficiency was 93 % with a current density of 19.6 mA cm−2 at −0.9 V vs. RHE.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Sb2(S,Se)3 is identified as a promising light‐harvesting material due to its excellent light‐harvesting capability, abundant elemental storage, and excellent stability. Here a hydrothermal method is ...demonstrated for the direct deposition of Sb2(S,Se)3 film, in which it is found that ethylenediaminetetraacetic acid (EDTA) as a strong coordination additive is able to control the nucleation and deposition process for obtaining high‐quality Sb2(S,Se)3 films. With that, a milestone performance of 10.5% efficiency is achieved. This efficiency achievement indicates the great potential of Sb2(S,Se)3 as an alternative next‐generation solar cell material.
Hydrothermal deposition under the assistance of ethylenediaminetetraacetic acid (EDTA) leads to a Sb2(S,Se)3 film with enhanced grain size and electrical conductivity. Solar cells with this absorber film overcome the power conversion efficiency barrier and reach 10.5%.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Unraveling the role of surface oxide on affecting its native metal disulfide’s CO2 photoreduction remains a grand challenge. Herein, we initially construct metal disulfide atomic layers and hence ...deliberately create oxidized domains on their surfaces. As an example, SnS2 atomic layers with different oxidation degrees are successfully synthesized. In situ Fourier transform infrared spectroscopy spectra disclose the COOH* radical is the main intermediate, whereas density-functional-theory calculations reveal the COOH* formation is the rate-limiting step. The locally oxidized domains could serve as the highly catalytically active sites, which not only benefit for charge-carrier separation kinetics, verified by surface photovoltage spectra, but also result in electron localization on Sn atoms near the O atoms, thus lowering the activation energy barrier through stabilizing the COOH* intermediates. As a result, the mildly oxidized SnS2 atomic layers exhibit the carbon monoxide formation rate of 12.28 μmol g–1 h–1, roughly 2.3 and 2.6 times higher than those of the poorly oxidized SnS2 atomic layers and the SnS2 atomic layers under visible-light illumination. This work uncovers atomic-level insights into the correlation between oxidized sulfides and CO2 reduction property, paving a new way for obtaining high-efficiency CO2 photoreduction performances.
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IJS, KILJ, NUK, PNG, UL, UM
Synergistic improvements in the electrical conductivity and catalytic activity for the oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) are of paramount importance for rechargeable ...metal–air batteries. In this study, one‐nanometer‐scale ultrathin cobalt oxide (CoOx) layers are fabricated on a conducting substrate (i.e., a metallic Co/N‐doped graphene substrate) to achieve superior bifunctional activity in both the ORR and OER and ultrahigh output power for flexible Zn–air batteries. Specifically, at the atomic scale, the ultrathin CoOx layers effectively accelerate electron conduction and provide abundant active sites. X‐ray absorption spectroscopy reveals that the metallic Co/N‐doped graphene substrate contributes to electron transfer toward the ultrathin CoOx layer, which is beneficial for the electrocatalytic process. The as‐obtained electrocatalyst exhibits ultrahigh electrochemical activity with a positive half‐wave potential of 0.896 V for ORR and a low overpotential of 370 mV at 10 mA cm−2 for OER. The flexible Zn–air battery built with this catalyst exhibits an ultrahigh specific power of 300 W gcat
−1, which is essential for portable devices. This work provides a new design pathway for electrocatalysts for high‐performance rechargeable metal–air battery systems.
Ultrathin cobalt oxide layers on the surface of a metallic cobalt/N‐doped graphene substrate synergistically enhance the electrical conductivity and catalytic activity, leading to high performance in oxygen reactions under alkaline conditions. A flexible Zn–air battery built with this electrocatalyst has an ultrahigh output power capability and a record‐high specific power of 300 W gcat
−1, which is essential for portable devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The concurrent transformation of carbon dioxide and water into hydrocarbons and oxygen by low-photonic-energy IR light still represents a huge challenge. Here, we design an ultrathin conductor ...system, in which the special partially occupied band serves as the mediator to simultaneously guarantee IR light harvesting and satisfy band-edge positions, while the ultrathin configuration improves charge separation rates and surface redox kinetics. Taking the low cost and earth-abundant CuS as an example, we first fabricate ultrathin CuS layers, where temperature-dependent resistivities, valence-band spectra, and theoretical calculations affirm their metallic nature. Synchrotron-radiation photoelectron and ultraviolet–visible–near-infrared spectra show that metallic CuS atomic layers could realize a new cooperative intraband–interband transition under IR light irradiation, where the generated electrons and holes could simultaneously involve the carbon dioxide reduction and water oxidation reactions. As a result, CuS atomic layers exhibit nearly 100% selective CO production with an evolution rate of 14.5 μmol g–1 h–1 under IR light irradiation, while the catalytic performance shows no obvious decay after a 96 h test. Briefly, benefiting from ultrahigh conductivity and a unique partially occupied band, abundant conductor materials such as conducting metal sulfides and metal nitrides hold great promise for applications as effective IR light responsive photocatalysts.
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IJS, KILJ, NUK, PNG, UL, UM
Nitrogen fixation in a simulated natural environment (i.e., near ambient pressure, room temperature, pure water, and incident light) would provide a desirable approach to future nitrogen conversion. ...As the NN triple bond has a thermodynamically high cleavage energy, nitrogen reduction under such mild conditions typically undergoes associative alternating or distal pathways rather than following a dissociative mechanism. Here, we report that surface plasmon can supply sufficient energy to activate N2 through a dissociative mechanism in the presence of water and incident light, as evidenced by in situ synchrotron radiation-based infrared spectroscopy and near ambient pressure X-ray photoelectron spectroscopy. Theoretical simulation indicates that the electric field enhanced by surface plasmon, together with plasmonic hot electrons and interfacial hybridization, may play a critical role in NN dissociation. Specifically, AuRu core-antenna nanostructures with broadened light adsorption cross section and active sites achieve an ammonia production rate of 101.4 μmol g–1 h–1 without any sacrificial agent at room temperature and 2 atm pressure. This work highlights the significance of surface plasmon to activation of inert molecules, serving as a promising platform for developing novel catalytic systems.
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IJS, KILJ, NUK, PNG, UL, UM
Z‐scheme water splitting is a promising approach based on high‐performance photocatalysis by harvesting broadband solar energy. Its efficiency depends on the well‐defined interfaces between two ...semiconductors for the charge kinetics and their exposed surfaces for chemical reactions. Herein, we report a facile cation‐exchange approach to obtain compounds with both properties without the need for noble metals by forming Janus‐like structures consisting of γ‐MnS and Cu7S4 with high‐quality interfaces. The Janus‐like γ‐MnS/Cu7S4 structures displayed dramatically enhanced photocatalytic hydrogen production rates of up to 718 μmol g−1 h−1 under full‐spectrum irradiation. Upon further integration with an MnOx oxygen‐evolution cocatalyst, overall water splitting was accomplished with the Janus structures. This work provides insight into the surface and interface design of hybrid photocatalysts, and offers a noble‐metal‐free approach to broadband photocatalytic hydrogen production.
Janus‐like structures consisting of γ‐MnS and Cu7S4 with high‐quality interfaces were obtained by facile cation exchange. The hybrid structures exhibit broadband light absorption and improved charge separation, which led to a hydrogen production rate of 718 μmol g−1 h−1 under full‐spectrum irradiation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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