Wide-Range High-Boost Turbocharging System Using Advanced Aerodynamic Design Features
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42 ENGINEERING↗
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Electron Redistributed S-Doped Nickel Iron Phosphides Derived from One-Step Phosphatization of MOFs for Significantly Boosting Electrochemical Water Splitting
Nonprecious transition metal-organic frameworks (MOFs) are one of the most promising precursors for developing electrocatalysts with high porosity and structural rigidity. This study reports the synthesis of high efficiency electrocatalysts based on S-doped NiFeP. MOF-derived S-doped NiFeP structure is synthesized by a one-step phosphorization process with using S-doped MOFs as the precursor, which is more convenient and environment friendly, and also helps retain the samples’ framework. The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance of the NiFeP catalysts can be improved after partially replacing P by S due to the tunable electronic structure. The optimized CCS-NiFeP-10 reaches a current density of 10 mA cm –2 for OER with an overpotential of 201 mV and outperforms most NiFe-based catalysts. The S doping plays an important role in tuning the ΔG values for intermediates formation in Ni atoms to a suitable value and exhibits a pronouncedly improved the OER performance. CCS-NiFeP-20 sample presents excellent HER performance due to the d-band center downshifting from the Fermi level. When the voltage of the electrolytic cell is 1.50 V, a current density of 10 mA cm –2 can be obtained. This strategy paves the way for designing highly active none-noble metal catalysts.
36 MATERIALS SCIENCE↗
Tailored Persistent Radical‐containing Heterotrimetal‐Organic Framework for Boosting Efficiency of Visible/NIR Light‐driven Photocatalytic CO 2 Reduction
Abstract Promoting light absorption range of photocatalysts is of great significance to improve solar light‐driven photocatalytic CO 2 reduction efficiency. Herein, a new viologen‐based multicomponent heterotrimetallic metal–organic framework (MOF) [Cu 3 Th 6 ( µ 3 ‐O) 4 ( µ 3 ‐OH) 4 (cpb) 12 ][Fe III (CN) 6 ] 6 (IHEP‐14) with an unprecedented (6, 18)‐connected she ‐ d topology is presented. Upon UV irradiation, this MOF undergoes ligand and iron photoreduction, and a single‐crystal‐to‐single‐crystal transformation to generate persistent radical‐containing MOF [Cu 3 Th 6 ( µ 3 ‐O) 4 ( µ 3 ‐OH) 4 (cpb • ) 12 ][Fe II (CN) 6 ] 6 (IHEP‐15). This radical‐containing MOF shows excellent stability without fading after at least 2 months in air. Besides extending the photoabsorption to a wider wavelength range covering from 200 to 2,500 nm, the generation of persistent radical in IHEP‐15 also largely enhances its CO 2 adsorption capacity by a factor of three due to the strong affinity between π orbital of the radical and the π system of CO 2 . These attributes endow IHEP‐15 with excellent visible/NIR light‐driven CO 2 photoreduction activity, with CO production rates under visible and NIR irradiation of 570.3 and 209.3 µmol h −1 g −1 , respectively. Notably, the latter is a record high for NIR‐induced CO production among all MOFs reported so far.
Hu, Kong‐Qiu↗
Modulating Electronic Structure of Atomically Dispersed Nickel Sites through Boron and Nitrogen Dual Coordination Boosts Oxygen Reduction
Abstract Atomically dispersed 3D transitional metal active sites with nitrogen coordination anchored on carbon support have emerged as a kind of promising electrocatalyst toward oxygen reduction reaction (ORR) in the field of fuel cells and metal–air cells. However, it is still a challenge to accurately modulate the coordination structure of single‐atom metal sites, especially first‐shell coordination, as well as identify the relationship between the geometric/electronic structure and ORR performance. Herein, a carbon‐supported single‐atom nickel catalyst is fabricated with boron and nitrogen dual coordination (denoted as Ni‐B/N‐C). The hard X‐ray absorption spectrum result reveals that atomically dispersed Ni active sites are coordinated with one B atom and three N atoms in the first shell (denoted as Ni‐B 1 N 3 ). The Ni‐B/N‐C catalyst exhibits a half‐wave potential ( E 1/2 ) of 0.87 V versus RHE, along with a distinguished long‐term durability in alkaline media, which is superior to commercial Pt/C. Density functional theory calculations indicate that the Ni‐B 1 N 3 active sites are more favorable for the adsorption of ORR intermediates relative to Ni‐N 4 , leading to the reduction of thermodynamic barrier and the acceleration of reaction kinetics, which accounts for the increased intrinsic activity.
Chemistry↗
Boosting Hydrogen Evolution in Neutral Medium by Accelerating Water Dissociation with Ru Clusters Loaded on Mo 2 CTx MXene
Abstract Electrocatalytic hydrogen evolution reaction (HER) in mild neutral medium is a compelling goal for environmentally sustainable energy conversion, but its development is greatly limited by slow kinetics. Platinum group noble metals exhibit ultra‐high HER activities, but their scarcity and performance instability restrict wide application. Herein, taking advantage of excellent catalyst carrier properties of 2D‐layered transition metal carbides (MXenes), highly dispersed of Ru clusters anchored on Mo 2 CT x MXene are demonstrated as a superior HER electrocatalyst, which is prepared by a facile in situ reduction strategy. The as‐prepared Ru/Mo 2 CT x catalyst exhibits a very low overpotential of 73 mV to achieve a current density of −10 mA cm −2 and Tafel slope of 57 mV dec −1 in neutral medium, surpassing performance of most previously reported MXene‐based catalysts. In addition, Ru/Mo 2 CT x catalyst also presents superior stability compared to commercial Pt/C. Experimental results and theoretical calculations indicate that the interaction between Ru clusters modulates the electronic structure of active sites and promotes H 2 O dissociation and hydrogen desorption.
Wu, Yanze↗
Incombustible Polymer Electrolyte Boosting Safety of Solid–State Lithium Batteries: A Review
Lithium-ion batteries with their portability, high energy density, and reusability are frequently used in today's world. Under extreme conditions, lithium-ion batteries leak, burn, and even explode. Therefore, improving the safety of lithium-ion batteries has become a focus of attention. Researchers believe using a solid electrolyte instead of a liquid one can solve the lithium battery safety issue. Due to the low price, good processability and high safety of the solid polymer electrolytes, increasing attention have been paid to them. However, polymer electrolytes can also decompose and burn under extreme conditions. Moreover, lithium dendrites are formed continuously due to the uneven charge distribution on the surface of the lithium metal anode. A short circuit caused by a lithium dendrite can cause the battery to thermal runaway. As a result, the safety of polymer solid-state batteries remains a challenge. In this review, the thermal runaway mechanism of the batteries is summarized, and the batteries abuse test standard is introduced. In addition, the recent works on the high-safety polymer electrolytes and the solution strategies of lithium anode problems in polymer batteries are reviewed. Finally, the development direction of safe polymer solid lithium batteries is prospected.
25 ENERGY STORAGE↗
Boosting Sodium Storage in TiO 2 Nanotube Arrays through Surface Phosphorylation
In this paper, sodium–ion batteries (SIBs) offer a promise of a scalable, low–cost, and environmentally benign means of renewable energy storage. However, the low capacity and poor rate capability of anode materials present an unavoidable challenge. In this work, it is demonstrated that surface phosphorylated TiO 2 nanotube arrays grown on Ti substrate can be efficient anode materials for SIBs. Fabrication of the phosphorylated nanoarray film is based on the electrochemical anodization of Ti metal in NH 4 F solution and subsequent phosphorylation using sodium hypophosphite. The phosphorylated TiO 2 nanotube arrays afford a reversible capacity of 334 mA h g –1 at 67 mA g –1 , a superior rate capability of 147 mA h g –1 at 3350 mA g –1 , and a stable cycle performance up to 1000 cycles. In situ X–ray diffraction and transmission electron microscopy reveal the near–zero strain response and robust mechanical behavior of the TiO 2 host upon (de)sodiation, suggesting its excellent structural stability in the Na+ storage application.
25 ENERGY STORAGE↗
3D‐Printed Structure Boosts the Kinetics and Intrinsic Capacitance of Pseudocapacitive Graphene Aerogels
Abstract The performance of pseudocapacitive electrodes at fast charging rates are typically limited by the slow kinetics of Faradaic reactions and sluggish ion diffusion in the bulk structure. This is particularly problematic for thick electrodes and electrodes highly loaded with active materials. Here, a surface‐functionalized 3D‐printed graphene aerogel (SF‐3D GA) is presented that achieves not only a benchmark areal capacitance of 2195 mF cm −2 at a high current density of 100 mA cm −2 but also an ultrahigh intrinsic capacitance of 309.1 µF cm −2 even at a high mass loading of 12.8 mg cm −2 . Importantly, the kinetic analysis reveals that the capacitance of SF‐3D GA electrode is primarily (93.3%) contributed from fast kinetic processes. This is because the 3D‐printed electrode has an open structure that ensures excellent coverage of functional groups on carbon surface and facilitates the ion accessibility of these surface functional groups even at high current densities and large mass loading/electrode thickness. An asymmetric device assembled with SF‐3D GA as anode and 3D‐printed GA decorated with MnO 2 as cathode achieves a remarkable energy density of 0.65 mWh cm −2 at an ultrahigh power density of 164.5 mW cm −2 , outperforming carbon‐based supercapacitors operated at the same power density.
asymmetric supercapacitors↗
Robust Oxygen‐Vacancy‐Engineered Co(OH) 2 /Cu Heterostructures Boost Nitrate Electroreduction to Ammonia beyond 2 A cm −2
Electrocatalytic nitrate reduction reaction (NO 3 RR) presents a sustainable paradigm for green NH 3 synthesis and NO 3 − wastewater valorization. However, overcoming sluggish NO 3 RR kinetics under industrial-current operation persists as a critical challenge. Herein, robust oxygen vacancy-enriched heterostructures (O v -Co(OH) 2 /Cu) are engineered through in situ electrochemical reconstruction. By coupling Cu-mediated NO 3 − -to-NO 2 − conversion with O v -Co(OH) 2 -accelerated NO 2 − -to-NH 3 transformation, this heterostructured system delivers an unprecedented NH 3 yield rate of 167.8 mg h −1 cm −2 and 97.7% Faradaic efficiency at >2 A cm −2 , while maintaining exceptional current tolerance over 25 h. Operando spectroscopic characterizations and theoretical calculations reveal that the introduction of O v in Co(OH) 2 synergistically accelerates water dissociation to ensure continuous hydrogen supply and optimizes *NOOH adsorption, reducing the energy barrier for the rate-limiting step (*NO 2 to *NOOH). To demonstrate practical viability, a membrane-electrode-assembly electrolyzer integrating NO 3 RR with glycerol oxidation reaction achieves highly effective co-production of NH 3 and formate alongside wastewater treatment. In conclusion, this work offers new insights into the rational design of electrocatalysts through in situ reconstruction-induced vacancy engineering for scalable and practical NO 3 RR applications.
ammonia synthesis↗
A Nanoscale Ternary Amide‐rGO Composite with Boosted Kinetics for Reversible H 2 Storage
Abstract Metal amides are attractive candidates for hydrogen storage due to their high volumetric and gravimetric hydrogen densities. However, the sluggish kinetics and competing side reactions during hydrogen uptake and release limit their practical use. Here, a novel nanoconfined Li 2 Mg(NH) 2 @reduced graphene oxide (rGO) composite is presented, which is fabricated using a melt‐infiltration method with a minimum weight penalty of only 2 wt.%. The presence of rGO ensures close contact between the active phases, effectively preventing aggregation during cycling process. As a result, the reversible capacity of Li 2 Mg(NH) 2 @rGO reaches 4.42 wt.%, with no capacity degradation observed after multiple cycling. Theoretical calculations show that rGO catalyzes the hydrogen bond cleavage at the Mg‐amide/Li hydride interface, leading to local dehydrogenation hotspots and significantly improves kinetics of dehydrogenation compared to the bulk counterpart. This study provides a promising strategy for designing metal imide‐based composites to overcome the kinetic limitations and improve their reversible hydrogen storage performance.
08 HYDROGEN↗
Surface Doping Boosts Triplet Generation Yield in Perovskite-Sensitized Upconversion
Triplet–triplet annihilation-based photon upconversion (TTA-UC) can efficiently generate higher energy photons at low relative fluences. Bulk metal halide perovskites have offered promise in efficiently sensitizing molecular triplet states in the solid state, necessary for the integration of TTA-UC into device-based applications. Recent work focused on TTA-UC from a rubrene triplet annihilator sensitized by perovskite thin films has established relatively efficient charge extraction from the perovskite, forming the triplet exciton in rubrene. Yet, the specifics underpinning charge transfer at the perovskite/rubrene interface are not fully elucidated. Here, to improve device performance and study the properties governing charge transfer at the interface, various organic solvents are explored to treat the perovskite surface. Scanning tunneling microscopy and spectroscopy show a difference in the electronic band structure, where both n- and p-type terminated perovskite surfaces are observed depending on the solvent used. Supported by optical spectroscopy, the impact of the perovskite electronic structure is monitored, indicating that n-type perovskite sensitizers feature higher TTA-UC efficiencies due to favorable band bending resulting in efficient hole-mediated triplet formation. Overall, the tuning of the electronic structure of the perovskite sensitizer through solvent treatment is shown to be a key force in tuning the mechanism of efficient triplet generation.
36 MATERIALS SCIENCE↗
Modulating Charge Transfer Efficiency of Hematite Photoanode with Hybrid Dual‐Metal–Organic Frameworks for Boosting Photoelectrochemical Water Oxidation
Abstract The glorious charge transfer efficiency of photoanode is an important factor for efficient photoelectrochemical (PEC) water oxidation. However, it is often limited by slow kinetics of oxygen evolution reaction. Herein, a dual transition metal‐based metal–organic frameworks (MOF) cocatalyst, Fe@Ni–MOF, is introduced into a titanium‐doped hematite (Fe 2 O 3 :Ti) photoanode. The combination of Ni and Fe can optimize the filling of 3d orbitals. Moreover, the introduction of Fe donates electrons to Ni in the MOF structure, thus, suppressing the irreversible (long‐life‐time) oxidation of Ni 2+ into Ni 3+ . The resulting Fe@Ni–MOF/Fe 2 O 3 :Ti photoanode exhibits ∼threefold enhancement in the photocurrent density at 1.23 V versus the reversible hydrogen electrode. Kinetic analysis of the PEC water oxidation processes indicates that this performance improvement is primarily due to modulating the charge transfer efficiency of hematite photoanode. Further results show that a single transition metal‐based MOF cocatalyst, Ni–MOF, exhibits slow charge transfer in spite of a reduction in surface charge recombination, resulting in a smaller charge transfer efficiency. These findings provide new insights for the development of photoelectrodes decorated with MOFs.
36 MATERIALS SCIENCE↗
Localized High‐Concentration Electrolytes Boost Potassium Storage in High‐Loading Graphite
Abstract Reversible intercalation of potassium‐ion (K + ) into graphite makes it a promising anode material for rechargeable potassium‐ion batteries (PIBs). However, the current graphite anodes in PIBs often suffer from poor cyclic stability with low coulombic efficiency. A stable solid electrolyte interphase (SEI) is necessary for stabilizing the large interlayer expansion during K + insertion. Herein, a localized high‐concentration electrolyte (LHCE) is designed by adding a highly fluorinated ether into the concentrated potassium bis(fluorosulfonyl)imide/dimethoxyethane, which forms a durable SEI on the graphite surface and enables highly reversible K + intercalation/deintercalation without solvent cointercalation. Furthermore, this LHCE shows a high ionic conductivity (13.6 mS cm −1 ) and excellent oxidation stability up to 5.3 V (vs K + /K), which enables compatibility with high‐voltage cathodes. The kinetics study reveals that K + intercalation/deintercalation does not follow the same pathway. The potassiated graphite exhibits excellent depotassiation rate capability, while the formation of a low stage intercalation compound is the rate‐limiting step during potassiation.
Qin, Lei↗
Boosting Superior Lithium Storage Performance of Alloy-Based Anode Materials via Ultraconformal Sb Coating–Derived Favorable Solid-Electrolyte Interphase
Alloy materials such as Si and Ge are attractive as high-capacity anodes for rechargeable batteries, but such anodes undergo severe capacity degradation during discharge-charge processes. Compared to the over-emphasized efforts on the electrode structure design to mitigate the volume changes, understanding and engineering of the solid-electrolyte interphase (SEI) are significantly lacking. This work demonstrates that modifying the surface of alloy-based anode materials by building an ultraconformal layer of Sb can significantly enhance their structural and interfacial stability during cycling. Combined experimental and theoretical studies consistently reveal that the ultraconformal Sb layer is dynamically converted to Li 3 Sb during cycling, which can selectively adsorb and catalytically decompose electrolyte additives to form a robust, thin, and dense LiF-dominated SEI, and simultaneously restrain the decomposition of electrolyte solvents. Hence, the Sb-coated porous Ge electrode delivers much higher initial Coulombic efficiency of 85% and higher reversible capacity of 1046 mAh g -1 after 200 cycles at 500 mA g -1 , compared to only 72% and 170 mAh g -1 for bare porous Ge. The present finding has indicated that tailoring surface structures of electrode materials is an appealing approach to construct a robust SEI and achieve long-term cycling stability for alloy-based anode materials.
25 ENERGY STORAGE↗
Bulk‐Heterojunction Electrocatalysts in Confined Geometry Boosting Stable, Acid/Alkaline‐Universal Water Electrolysis
Abstract Alkaline water splitting electrocatalysts have been studied for decades; however, many difficulties remain for commercialization, such as sluggish hydrogen evolution reaction (HER) kinetics and poor catalytic stability. Herein, by mimicking the bulk‐heterojunction morphology of conventional organic solar cells, a uniform 10 nm scale nanocube is reported that consists of subnanometer‐scale heterointerfaces between transition metal phosphides and oxides, which serves as an alkaline water splitting electrocatalyst; showing great performance and stability toward HER and oxygen evolution reaction (OER). Interestingly, the nanocube electrocatalyst reveals acid/alkaline independency from the synergistic effect of electrochemical HER (cobalt phosphide) and thermochemical water dissociation (cobalt oxide). From the spray coating process, nanocube electrocatalyst spreads uniformly on large scale (≈6.6 × 5.6 cm 2 ) and is applied to alkaline water electrolyzers, stably delivering 600 mA cm −2 current for >100 h. The photovoltaic‐electrochemical (PV‐EC) system, including silicon PV cells, achieves 11.5% solar‐to‐hydrogen (STH) efficiency stably for >100 h.
Chemistry↗
Merging Photoredox and Organometallic Catalysts in a Metal-Organic Framework Significantly Boosts Photocatalytic Activities
Abstract not provided
Zhu, Yuan-Yuan↗