Mass Transport Channels Research Articles

Elaborate construction of a MOF-derived novel morphology Z-scheme ZnO/ZnCdS heterojunction for enhancing photocatalytic H2 evolution and tetracycline degradation

Elaborate construction of novel Z-scheme heterojunction with exceptional morphology derived from metal-organic framework (MOF) have been attracted greatly interest for improving the photocatalytic ability. Herein, a Z-scheme ZnO/ZnCdS heterojunction of rare morphology with ultrathin-nanosheet assembled hierarchical morphology ZnCdS supporting on rich gap ZnO nanospheres were constructed from Zn-based MOF (namely PZH-139) for the first time. This unique feature increased specific surface area, offered abundant mass transport channels and accessible catalytic active sites, accelerated electron migration, which highly elevated photocatalytic property. Furthermore, electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) calculations confirmed the reservation of strong redox capability owing to Z-scheme electron transfer path and the ΔGH* closer to zero of Z-scheme ZnO/ZnCdS system were another two key factors for boosting the photocatalytic activity. As a result, 3-ZnO-700/ZnCdS-160 with optimal morphology showed the best H2 generation performance of 15.43 mmol h−1 g−1 and degradation tetracycline (TC) efficiency of 98.14 %. This work offered a novel and feasible idea for elaborate synthesis of the high-efficiency Z-scheme ZnO/ZnCdS heterojunction with special morphology derived from Zn-MOF.

Linker-induced hollow MOF embedded into arginine-modified montmorillonite for efficient urea removal: Adsorption behavior and mechanism analysis

The precise regulation of hollow metal–organic framework (HMOF) and the effective assembly with excellent guest materials present limitless potential for pollutant removal. In this work, the arginine-modified montmorillonite (AMMT) was preferentially prepared via room temperature impregnation approach, and then the AMMT-HMOF composite was effectively constructed through a one-pot method. During this process, linker-induced MOF to MOF route was proposed, i.e., solid ZIF-67 transformed into hollow MOF-74 (thicknesses: ∼25 nm). Of note, this route involves the transition from solid to hollow structures, as well as the change between different topologies. Next, the AMMT-HMOF composite was evaluated for adsorption experiments with urea in aqueous solution as the target molecule. Further speaking, the optimization experiments were conducted to analyze the impact of pH, contact time, adsorbent mass and original urea concentration towards the adsorption process. The as-fabricated absorbent presented a maximum adsorption capacity of 298.5 mg/g within 1 h, demonstrating adherence to pseudo-second-order kinetics and the Langmuir model. The excellent adsorption performance can be ascribed to the enlarged layer spacing of AMMT, as well as the fast mass transport and abundant diffusion channels in HMOF. Additionally, the mechanistic analyses revealed the existence of hydrogen bonding interactions between the adsorbent and urea. Meanwhile, the adsorbent displayed the outstanding morphological and structural stability after usage. According to our survey, this is the first time to use this linker-induced MOF-to-MOF strategy and predictably assemble with functionalized montmorillonite to construct the hollow MOF composite for urea adsorption.

Sub-8 nm networked cage nanofilm with tunable nanofluidic channels for adaptive sieving

Biological cell membrane featuring smart mass-transport channels and sub-10 nm thickness was viewed as the benchmark inspiring the design of separation membranes; however, constructing highly connective and adaptive pore channels over large-area membranes less than 10 nm in thickness is still a huge challenge. Here, we report the design and fabrication of sub-8 nm networked cage nanofilms that comprise of tunable, responsive organic cage-based water channels via a free-interface-confined self-assembly and crosslinking strategy. These cage-bearing composite membranes display outstanding water permeability at the 10−5 cm2 s−1 scale, which is 1–2 orders of magnitude higher than that of traditional polymeric membranes. Furthermore, the channel microenvironments including hydrophilicity and steric hindrance can be manipulated by a simple anion exchange strategy. In particular, through ionically associating light-responsive anions to cage windows, such ‘smart’ membrane can even perform graded molecular sieving. The emergence of these networked cage-nanofilms provides an avenue for developing bio-inspired ultrathin membranes toward smart separation.

Hierarchical FeOxHy@Ni3B hybrid for efficient alkaline oxygen evolution at high current density

Electrocatalysts with high activity and long-term durability are vital toward large-scale hydrogen production from electrocatalytic water splitting. Here, the self-supported electrode (FeOxHy@Ni3B/NF) with hierarchical heterostructure was simply prepared by using Ni3B chunks grown on nickel foam as substrate to in situ form vertical FeOxHy nanosheets. Such hybrid shows efficient oxygen evolution reaction activity with overpotentials as low as 267 and 249 mV at 100 mA cm−2 in 1 M KOH solution and 30 wt% KOH solution, respectively. Meanwhile, it also exhibits excellent catalytic stability, sustaining catalysis at 500 mA cm−2 in 1 M KOH solution for 200 h, and even for 200 h at 1000 mA cm−2 in 30 wt% KOH solution. Further experimental results reveal that the FeOxHy@Ni3B/NF is endowed with superhydrophilic and superaerophobic surface properties, which not only provide more mass transport channels, as well as facilitated the diffusion of reaction intermediates and gas bubbles. Also, it holds faster reaction kinetics, more accessible active sites and accelerated electron transfer rates due to strong synergistic interactions at the heterogeneous interface.

Confined MOF pyrolysis within mesoporous SiO2 core–shell nanoreactors for superior activity and stability of electro-Fenton catalysts

Despite the high density and uniform distribution of active sites in metal–organic frameworks (MOFs) and their derivatives, the relatively low stability in water still limits their utilization in heterogeneous catalysis. Herein, the confinement of pyrolyzed MIL-88B(Fe) derivatives within mesoporous SiO2 allowed fabricating core–shell nanoreactors (Fe/C@mSiO2) that served as heterogeneous electro-Fenton (HEF) catalysts for the first time, revealing an excellent performance. The as-prepared catalysts were featured by high specific surface area and dense active sites. During service as core–shell nanoreactors, they behaved as a dual function adsorbent-catalyst, exhibiting superior catalytic activity and recyclability as compared to HEF catalysts without shell. Using 0.2 g/L of catalyst, the complete removal of bisphenol A at pH 6.2 and 100 mA was achieved at 120 min, with extremely low iron leaching of 0.11 mg/L. The rigid mSiO2 shell not only protected the iron active sites from leaching, but it also provided porous and permeable channels for efficient mass transport. The unique core–shell architecture concentrates the catalytic sites and reactants within a confined space, promoting the fast degradation of bisphenol A. Furthermore, the defect-rich carbon substrate and the high dispersibility of iron-rich sites favor a fast electron transfer. The efficient treatment of several organic micropollutants in consecutive trials corroborated the high activity and stability of the Fe/C@mSiO2. This work contributes to the rational design of HEF catalysts, aiming at consolidating their practical application in advanced wastewater treatment.

Three-dimensional bimodal pore-rich G/MXene sponge amalgamated with vanadium diselenide nanosheets as a high-performance electrode for electrochemical water-oxidation/reduction reactions.

Exploring new strategies to design non-precious and efficient electrocatalysts can provide a solution for sluggish electrocatalytic kinetics and sustainable hydrogen energy. Transition metal selenides are potential contenders for bifunctional electrocatalysis owing to their unique layered structure, low band gap, and high intrinsic activities. However, insufficient access to active sites, lethargic water dissociation, and structural degradation of active materials during electrochemical reactions limit their activities, especially in alkaline media. In this article, we report a useful strategy to assemble vanadium diselenide (VSe2) into a 3D MXene/rGO-based sponge-like architecture (VSe2@G/MXe) using hydrothermal and freeze-drying approaches. The 3D hierarchical meso/macro-pore rich sponge-like morphology not only prevents aggregation of VSe2 nanosheets but also offers a kinetics-favorable framework and high robustness to the electrocatalyst. Synergistic coupling of VSe2 and a MXene/rGO matrix yields a heterostructure with a large specific surface area, high conductivity, and multi-dimensional anisotropic pore channels for uninterrupted mass transport and gas diffusion. Consequently, VSe2@G/MXe presented superior electrochemical activity for both the HER and OER compared to its counterparts (VSe2 and VSe2@G), in alkaline media. The overpotentials required to reach a cathodic and anodic current density of 10 mA cm-2 were 153 mV (Tafel slope = 84 mV dec-1) and 241 mV (Tafel slope = 87 mV dec-1), respectively. The Rct values at the open circuit voltage were as low as 9.1 Ω and 1.41 Ω for the HER and OER activity, respectively. Importantly, VSe2@G/MXe withstands a steady current output for a long 24 h operating time. Hence, this work presents a rational design for 3D microstructures with optimum characteristics for efficient bifunctional alkaline water-splitting.

Tailoring Binding Abilities By Incorporating Oxophilic Transition Metals on 3D Nanostructured Ni Arrays for Accelerated Alkaline Hydrogen Evolution Reaction

Developing efficient and inexpensive electrocatalysts for the hydrogen evolution reaction (HER) in alkaline water electrolysis plays a key role for renewable hydrogen energy technology. The slow reaction kinetics of HER in alkaline solutions, however, has hampered advances in high-performance hydrogen production. Herein, we investigated the trends in HER activity with respect to the binding energies of Ni-based thin film catalysts by incorporating a series of oxophilic transition metal atoms. It was found that the doping of oxophilic atoms enables the modulation of binding abilities of hydrogen and hydroxyl ions on the Ni surfaces, leading to the first establishment of a volcano relation between OH-binding energies and alkaline HER activities. In particular, Cr-incorporated Ni catalyst shows optimized OH-binding as well as H-binding energies for facilitating water dissociation and improving HER activity in alkaline media. Further enhancement of catalytic performance was achieved by introducing an array of three-dimensional (3D) Ni nanohelixes (NHs) that provide abundant surface active sites and effective channels for charge transfer and mass transport. The Cr dopants incorporated into the Ni NHs accelerate the dissociative adsorption process of water, resulting in remarkably enhanced catalytic activities in alkaline medium. Our approach can provide a rational design strategy and experimental methodology toward efficient bimetallic electrocatalysts for alkaline HER using earth-abundant elements.Reference Journal of the American Chemical Society 3, 1399-1408 (2021) [Front Cover]

Efficient Bifunctional Oxygen Electrocatalysts for Rechargeable Zn−air Batteries Derived from Ni‐modified Prussian Blue

AbstractThe rational design and exploration of efficient, low‐cost and durable bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key to the development of rechargeable metal−air batteries. Here, we report a novel approach to in‐situ synthesize Fe0.64Ni0.36 nanoalloy encapsulated in nitrogen‐doped porous carbon nanotubes (FeNi@N−CNTs) as bifunctional electrocatalyst derived from Ni‐modified Prussian blue, on which the ORR/OER can be promoted by the N−CNTs surface due to the electron modulation caused by electron transfer from the inner FeNi nanoalloy to the N−CNTs surface. The abundant wide‐size range of mesopores in N−CNTs can offer rapid mass transport channels to facilitate the catalytic reactions. In addition, the encapsulation structure endows the outer N−CNTs acting as a “shield” to prevent the inner FeNi nanoalloy from corrosion in strong basic medium. Thanks to the synergistic effect between the N−CNTs and FeNi nanoalloy, the obtained FeNi@N−CNTs exhibits excellent bifunctional oxygen catalytic activity together with outstanding performance and cycling durability in rechargeable Zn−air battery. This work will open new avenues for the development of advanced bifunctional electrocatalysts for other metal−air batteries.

Multilayer Superlattices of Monolayer Mesoporous Carbon Framework‐Intercalated MXene for Efficient Capacitive Energy Storage

AbstractIncorporating conductive and porous components as pillaring materials into the interlayers of two‐dimensional (2D) materials offers a solution to the restacking issue and enables the creation of multifunctional hetero‐superstructures. Here, multilayer MXene superlattices intercalated with monolayer mesoporous carbon frameworks (MMCFs) are synthesized by colloidal co‐assembly of MXene Ti3C2Tx nanosheets and Fe3O4 nanoparticles. The intercalated MMCFs not only increase interlayer spacing and create porous channels for fast mass transport but also act as conductive pillars to facilitate electron transfer along the z‐direction. These unique structural features allow for the full utilization of unilamellar MXene, making the resulting Ti3C2Tx/MMCF superlattices particularly suitable for capacitive energy storage in organic electrolytes containing bulky ions. As a demonstration, supercapacitors made from Ti3C2Tx/MMCFs exhibit a volumetric capacitance of 317 F cm−3 in a tetraethylammonium tetrafluoroborate/propylene carbonate electrolyte. Furthermore, on‐chip micro‐supercapacitors (MSCs) fabricated from Ti3C2Tx/MMCFs, using the ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate as an electrolyte, achieve an areal energy density of 0.10 mWh cm−2, surpassing that of most state‐of‐the‐art MXene‐based MSCs developed to date. This study not only highlights the significant potential of Ti3C2Tx/MMCFs for efficient capacitive energy storage in organic electrolytes but also introduces a new method for synthesizing 2D porous hetero‐superstructures for various applications.

Fabrication of angstrom-scale two-dimensional channels for mass transport.

Fluidic channels at atomic scales regulate cellular trafficking and molecular filtration across membranes, and thus play crucial roles in the functioning of living systems. However, constructing synthetic channels experimentally at these scales has been a significant challenge due to the limitations in nanofabrication techniques and the surface roughness of the commonly used materials. Angstrom (Å)-scale slit-like channels overcome such challenges as these are made with precise control over their dimensions and can be used to study the fluidic properties of gases, ions and water at unprecedented scales. Here we provide a detailed fabrication method of the two-dimensional Å-scale channel devices that can be assembled to contain a desired number of channels, a single channel or up to hundreds of channels, made with atomic-scale precision using layered crystals. The procedure includes the fabrication of the substrate, flake, spacer layer, flake transfers, van der Waals assembly and postprocessing. We further explain how to perform molecular transport measurements with the Å-channels to directly probe the intriguing and anomalous phenomena that help shed light on the physics governing ultra-confined transport. The procedure requires a total of 1-2 weeks for the fabrication of the two-dimensional channel device and is suitable for users with prior experience in clean room working environments and nanofabrication.

Engineering anion defects of ternary V-S-Se layered cathodes for ultrafast zinc ion storage

In this work, a novel stainless-steel (SS) supported lattice-mismatched V-S-Se layered compound (VSySe2−x-SS) with high selenium (Se) vacancy was synthesized by tailoring the molar ratio of S to Se. The difference between the radii of Se and S results in lattice mismatches for a large number of Se vacancies, and the highest vacancy with the ultrafast zinc (Zn) storage performance are achieved by tuning a molar ratio of sulfur (S) to Se. More interestingly, with the introduction of Se vacancies, additional redox peaks of S appear, and creates more mass-transport channels as well as active sites for Zn2+ toward fast reaction kinetics. Density functional theory (DFT) calculations confirm that the Se defects can also effectively reduce the adsorption energy of Zn2+ ions on VS0.5Se2−x-SS for more reversible adsorption/desorption process of Zn2+ ions. Consequently, the specific capacity of the VS0.5Se2−x-SS electrode is as high as 188.1 mAh g−1 after 70 cycles at 0.6 A g−1, while accomplishing an excellent rate capability and satisfactory cycle stability. In addition, an assembled flexible quasi-solid state VS0.5Se2−x-SS//Zn battery also display good cycle stability, excellent electrochemical performance, and good environmental adaptability under different malignant environments including bending, soaking, hammering, weighing, washing and cutting. This work demonstrates a facile approach for electrode modifications used in Zn2+ ion batteries, holding great promise for practical applications and shedding lights on fundamentals of defects effects on battery performance.

Fabrication of transparent and hazy cellulosic light-management film for enhancing photon utilization in photocatalytic membrane process

Given the high demand of photocatalytic membrane filtration processes on both mass transport and light-utilization, this work introduces a novel transparent and highly porous cellulose film (P-RCF) that can serve as a light management layer to enhance the photon utilization of photocatalytic membrane processes. The built-in micron-sized pores act not only as channels for mass transport (filtration resistance ∼5 × 1010/m) but also as forward scatterers to endow the film with a high transmission haze (∼77%) without impairing its transmittance (∼90%). A g-C3N4 membrane with attached P-RCF (P-RCF@C3N4) exhibited enhanced photocatalytic activity for both tetracycline (TC) oxidation and Cr(VI) reduction. Moreover, by adjusting the incident light angle from 0° to 50°, the observed TC degradation kinetics on P-RCF@C3N4 became more stable than those on the bare g-C3N4 membrane, exhibiting incident-angle-independent properties. This enhanced photocatalytic performance can be attributed to the synergistic effect of refractive-index matching and light scattering within our transparent film, which reduces light reflection and traps the light inside at the photoactive layer, resulting in extended light propagation and utilization. This study provides a novel and versatile strategy for developing light management techniques for advanced photocatalytic membrane systems.

Pomegranate-Like FeNC with Optimized FeN4 Configuration as Bi-Functional Catalysts for Rechargeable Zinc-Air Batteries.

Catalysts with FeNC moieties have demonstrated remarkable activity toward oxygen reduction reaction (ORR), but precise synthesis and configuration regulation of FeNC to achieve bi-functional catalytic sites for ORR and oxygen evolution reaction (OER) remain a great challenge. Herein, a pomegranate-like catalyst with optimized FeN4 configuration is designed. The unique framework affords a large surface area for sufficient active site exposure and abundant macroporous channels for mass transport. By twisting chemical bonds, the electronic structure of FeN4 is regulated, and the adsorption/desorption of oxygen species is facilitated. Compared to noble metal-based catalysts (Pt/C+IrO2 ), the optimized FeNC exhibits impressive onset potential (0.96V versus reversible hydrogen electrode), larger limiting current density (5.85mA cm-2 ), and better long-term life for ORR, as well as, lower OER overpotential. When integrated into Zn-air batteries, it demonstrates a respectable peak power density (71.6mW cm-2 ) and ideal cycling stability (30h), exceeding that of commercial Pt/C+IrO2 . The exploration offers a guideline for designing advanced bi-functional electrocatalysts.

3D‐Printed Graded Electrode with Ultrahigh MnO2 Loading for Non‐Aqueous Electrochemical Energy Storage

AbstractElectrolytic manganese dioxide is one of the promising cathode candidates for electrochemical energy storage devices due to its high redox capacity and ease of synthesis. Yet, high‐loading MnO2 often suffers from sluggish reaction kinetics, especially in non‐aqueous electrolytes. The non‐uniform deposition of MnO2 on a porous current collectors also makes it difficult to fully utilize the active materials at high mass loading. Here, a 3D printed graded graphene aerogel (3D GA) that contains sparsely separated exterior ligaments is developed to create large open channels for mass transport as well as densely arranged interior ligaments providing large ion‐accessible active surface. The unique structural design homogenizes the thickness of electro deposited MnO2 even at an ultrahigh mass loading of ≈70 mg cm−2. The electrode achieves a remarkable volumetric capacity of 29.1 mA h cm−3 in the non‐aqueous electrolyte. A Li‐ion hybrid capacitor device assembled with a graded 3D GA/MnO2 cathode and graded 3D GA/VOx anode exhibits a wide voltage window of 0–4 V and a superior volumetric energy density of 20.2 W h L−1. The findings offer guidance on 3D printed electrode design for supporting ultrahigh loading of active materials and developments of high energy density energy storage devices.

Te-doped NiFe2O4 stabilized by amorphous carbon layers derived from one-step topological transitions of NiFe LDHs with significantly enhanced oxygen evolution reaction

Constructing efficient oxygen evolution reaction (OER) electrocatalysts that can stably operate under high temperatures and strong alkaline conditions still faces great challenges for industrial hydrogen production from water electrolysis. Herein, a self-supported tellurium (Te)-doped spinel NiFe2O4 with a carbon-stabilized nanosheet structure anodic catalyst on nickel foam (NF) (Te-NiFe2O4@C/NF) is successfully synthesized by calcination of a layered double hydroxide precursor (NiFe LDH). Benefiting from Te doping as well as coupling with the amorphous carbon layer and the unique superhydrophilic/aerophobic surface property, which provides efficient mass transport channels and rapid electron transport, the optimized Te-NiFe2O4@C/NF requires an overpotential of 220 mV to achieve a current density of 10 mA cm−2 for the OER in 1 M KOH at 25 ℃. Furthermore, an extremely low overpotential of 180 mV is required to achieve 500 mA cm−2 in 6 M KOH at 80 ℃ and maintains superior stability over 60 h under such harsh quasi-industrial conditions. Density functional theory calculations further reveal that Te doping can effectively modulate the local electronic environment of the Ni and Fe sites, which optimizes the intermediate (*OH) adsorption and facilitates the OER kinetics. This work may open up opportunities to explore efficient electrocatalysts for scalable hydrogen production.

Ultra-thin and ultra-light self-lubricating layer with accelerated dynamics for anode-free lithium metal batteries

Fabricating superior artificial interlayer with ingeniously controlled charge and mass transport channels without compromise in cell mass and volume is urgent but challenging for practical Lithium metal batteries (LMBs). Herein, inspired by Brasenia schreberi, a natural aquatic plant with unique polysaccharides biological channels for lubricating H2O transport, an ultrathin (137 nm) and ultralight (0.1 mg cm−2) self-lubricating ion-confined artificial layer (SLIC) is proposed to improve charge/mass transport of LMBs. A large-scale feasibility roll-to-roll technology coupled with self-assembly of phase-transitioned lysozyme (PTL) was employed to construct the flexible and cost-effective SLIC. The luxurious polar functional groups of PTL favor Li+ transport by facilitating Li+ de-solvation and charge transfer processes, while the unique microporous channels within PTL can regulate the Li+ concentration field and accelerate homogenized mass transport. Therefore, with such unique SLIC, dendrite-free Li plating/stripping was achieved and superior cycle performance for 850 cycles in Li||Cu cells was realized. Furthermore, the SLIC endows pouch cells and coin cells with remarkably improved performance in harsh conditions (high cathode loading, low N/P up to anode-free). More importantly, all processes for preparing such controllable and scalable SLIC film are done in ambient conditions without specific engineering difficulties, showing excellent prospects for practical application.

Boron pretreatment promotes phosphorization of FeNi catalysts for oxygen evolution

Oxygen evolution reaction (OER) is a crucial half-reaction for many energy conversion technologies, which requires efficient catalysts to boost its sluggish kinetics. Herein, the FeNi catalyst with a high phosphating level (HP-FexNi2−xP) is constructed by a three-step synthetic route: (i) hydrothermal deposition of lamellar sheets, (ii) NaBH4 pretreatment, and (iii) in situ phosphorization. FeNi layered double lamellar hydroxides were synthesized as the pre-catalysts. Then NaBH4 pretreatment was used to remove the oxide impurities and introduce oxygen vacancies to promote phosphorization in the subsequent process. Finally, HP-FexNi2−xP nanosheets were achieved, with several advantages like abundant exposed active sites, high conductivity, and accessible mass transport channels. During the OER process, FeNiOOH/HP-FexNi2−xP interfaces are formed through spontaneous electrochemical activation and surface reconstruction. Benefitting from the synergistic interfacial effect and abundant exposed active sites, the NiFe based catalysts show an overpotential of ≈ 208 mV to reach 10 mA cm−2 in 1 M KOH, and a stability of 200 h at 1 A cm−2. Overall, this work reports the rational design and preparation of a highly active OER catalyst, but also provides a general route through NaBH4 pretreatment, which can be usefully applied to promote phosphorization in other systems of interest for catalytic applications.

Superfast Mass Transport of Na/K Via Mesochannels for Dendrite-Free Metal Batteries.

Fast ion diffusion in anode hosts enabling uniform distribution of Li/Na/K is essential for achieving dendrite-free alkali-metal batteries. Common strategies, e.g. expanding the interlayer spacing of anode materials, can enhance bulk diffusion of Li but are less efficient for Na and K due to their larger ionic radius. Herein, a universal strategy to drastically improve the mass-transport efficiency of Na/K by introducing open mesochannels in carbon hosts is proposed. Such pore engineering can increase the accessible surface area by one order of magnitude, thus remarkably accelerating surface diffusion, as visualized by in situ transmission electron microscopy. In particular, once the mesochannels are filled by theNa/K metals, they become the superfast channels for mass transport via the mechanism of interfacial diffusion. Thus-modified carbon hosts enable Na/K filling in their inner cavities and uniform deposition across the whole electrodes with fast kinetics. The resulting Na-metal anodes can exhibit stable dendrite-free cycling with outstanding rate performance at a high current density of up to 30mA cm-2 . This work presents an inspiring attempt to address the sluggish transport issue of Na/K, as well as valuable insights into the mass-transport mechanism in porous anodes for high-performance alkali-metal storage.

Synergistic Coupling of Hierarchical Heterostructured Ni3P/Ni/VN Microflower Electrocatalyst for Enhanced Hydrogen Evolution Reaction

AbstractThe exploration of economical and highly efficient electrocatalysts for hydrogen evolution reaction (HER) is paramount for the development of sustainable hydrogen economy. Herein, a novel three‐dimensional (3D) hierarchical microflower electrocatalyst comprised of N‐doped carbon‐armored Ni3P/Ni/VN heterogeneous nanoparticles (Ni3P/Ni/VN@NC) is developed by combining a hydrothermal method with in‐situ carbonization‐phosphating strategy. The unique robust hierarchical structure derived from 3D NiV layered double hydroxide (NiV‐LDH) skeleton as precursor provides multidimensional mass and charge transport channels as well as numerous active sites for HER, leading to the improved HER activity. More importantly, the possible electron transfer route of Ni3P→Ni→VN is demonstrated due to the charge pumping capability of VN during interfacial electron intercoupling among the tri‐component, which endows Ni3P/Ni/VN with the favorable absorption of hydrogen‐intermediates and thus upgraded HER kinetics over such heterostructure. The resulting Ni3P/Ni/VN@NC catalyst exhibits extremely low overpotentials of 81 mV and 134 mV to deliver a current density of 10 mA cm−2 without iR‐compensation in alkaline and acidic media, respectively, and maintains continuous operation for over 90 h. This work enlightens the rational design of hierarchical multi‐component heterostructured catalysts for efficient hydrogen production.

All‐Dielectric Insulated 3D Plasmonic Nanoparticles for Enhanced Self‐Floating Solar Evaporation under One Sun

AbstractPlasmonic absorbers, featured by unique capability of broadband light absorption and nanoscale optical concentration, have long been regarded as ideal candidates for self‐floating interfacial solar evaporation yet suffering from low energy transfer efficiency because of poor thermal localization. In this work, by implanting an ion beam exfoliation of the continuous metallic film from the gold/nanoporous alumina template (Au/NPT), the all‐dielectric insulated plasmonic absorbers are demonstrated as efficient self‐floating interfacial solar evaporators with measured efficiency of ≈80% under one sun, which shows a ≈20% increment to conventional Au/NPT and is comparable to mainstream complicated carbon‐based evaporators with external thermal insulators. The enhanced energy transfer process can be ascribed to synergistic effect of plasmon‐enhanced solar absorption, broadband light induced thermal localization and/or insulation, as well as efficient mass transport channels. The results here would provide a new insight in underlying understanding and inspire further development of plasmonic solar thermal conversion.