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The wide accessibility to nanostructures with high uniformity and controllable sizes and morphologies provides great opportunities for creating complex superstructures with unique functionalities. Employing anisotropic nanostructures as the building blocks significantly enriches the superstructural phases, while their orientational control for obtaining long-range orders has remained a significant challenge. One solution is to introduce magnetic components into the anisotropic nanostructures to enable precise control of their orientations and positions in the superstructures by manipulating magnetic interactions. Recognizing the importance of magnetic anisotropy in colloidal assembly, we provide here an overview of magnetic field-guided self-assembly of magnetic nanoparticles with typical anisotropic shapes, including rods, cubes, plates, and peanuts. The Review starts with discussing the magnetic energy of nanoparticles, appreciating the vital roles of magneto-crystalline and shape anisotropies in determining the easy magnetization direction of the anisotropic nanostructures. It then introduces superstructures assembled from various magnetic building blocks and summarizes their unique properties and intriguing applications. It concludes with a discussion of remaining challenges and an outlook of future research opportunities that the magnetic assembly strategy may offer for colloidal assembly.

Abstract Interfacial solar steam generation holds great promise in water desalination thanks to its high energy efficiency by heating only the top layer of water for evaporation. While three‐dimensional (3D) evaporators have been proven to increase the evaporation rate by harnessing the energy from the surroundings, further development is still required in terms of convenient fabrication with potential scalability. Herein, we propose to overcome this challenge by using a high internal phase emulsion (HIPE) to template the synthesis of 3D hierarchically porous evaporators. The HIPE‐templated synthesis combined with a molding process can efficiently fabricate the desired 3D shape without wasting any materials and generate a hierarchically porous internal structure for continuous water supply. Engineering the overall shape and internal pores produces a 3D evaporator that can suppress conduction heat loss and efficiently collect thermal energy from its surroundings, boosting the evaporation rate to 2.82 kg/(m2 h) under 1‐sun illumination, which is significantly higher than conventional 2D evaporators. HIPE‐templating synthesis is an easy but effective way to produce various porous polymers, promising for a wide range of applications where easy production, excellent shape control, and potential scalability are critical.

The conventional phase-locked loops or frequency-locked loops should take time to calibrate the oscillator’s resonant frequency in a super-regenerative receiver (SRR) and severely disrupts the receiver’s operations. This paper proposes a novel intermittent frequency locked loop (IFLL) as a frequency synthesizer to continuously maintain the resonant frequency equal to the preset target frequency without interruption to the SRR. An analog loop mainly composed of a time-register-based frequency detector and a charge pump is proposed to achieve precise frequency detection during each SRR’s quenching period regardless of the inevitable initial phase error, and adjust SRR’s resonant frequency accordingly. An average fractional division scheme is adopted to improve IFLL’s frequency resolution to the level of the quenching frequency. The operations of the IFLL are analyzed with the z-domain transfer function, including the stability and frequency response. A prototype is built and tested. The measurement results show that the proposed IFLL only needs a calibration cycle of fewer than 50 $\mu \text{s}$ to adjust SRR’s resonant frequency without interruption against its receiving. The real-time frequency error after calibration is smaller than 70 kHz. SRR opposes a sensitivity of −61.2 dBm @ 200 kbps and a 3-dB bandwidth of 2.2 MHz.

A Bandgap reference (BGR) circuit with a new high-order curvature-compensation technique is proposed in this paper. The curvature method operates by adding up two correction voltages. The first one is proportional to the difference in gate-source voltages of two MOS transistors ( $\Delta V_{\mathrm {GS}}$ ) operating in weak inversion mode, while the second one ( $V_{\text {NL}}$ ) is generated using a nonlinear current created by a piecewise-linear circuit. To improve the power supply rejection ratio (PSRR) and the line regulation performance, a low-power pre-regulator isolates the circuit power supply and BGR output. Additionally, the chopping technique reduces the output voltage noise and offset. Consequently, the overall PVT robustness of the proposed circuit is significantly improved. The circuit was implemented using a thick-oxide transistor in a standard $0.18 \mathrm {\mu m}$ CMOS technology with a 3.3 V power supply voltage. The silicon results exhibit a temperature coefficient of 5–15 ppm/°C in the temperature range of −10 °C to 110 °C, whereas the simulated results demonstrate a similar performance within the temperature range of −40 °C to 150 °C. The supply current consumption is $150 ~\mu \text{A}$ , and the chip area is $0.56\times0.8$ mm2. The measured peak noise at the output is $1.42 ~\mu \text{V}/\sqrt {\text {Hz}} $ @320 Hz, the measured PSRR @ 1 kHz is −80 dB, and the line regulation performance is 10 ppm/V, making the proposed circuit suitable for applications requiring low noise, high-order temperature compensation, and robust PVT performance.

Abstract As a distinct type of nanocapsules, hollow superstructures of inorganic nanoparticles have attracted increasing attention due to their controllable permeability, convenient functionalization, and efficient surface utilization. Conventionally, they are produced by assembling nanoparticles against expensive sacrificial templates. Herein, a general emulsion‐based method is reported to assemble colloidal nanoparticles into submicron hollow superstructures, involving first co‐assembly of colloidal nanoparticles with organic additives to form clusters, then overcoating the clusters with a polymer shell, and finally removing the organic additives and re‐dispersing nanoparticles by exposing to a good solvent. The key to the success of this process is the re‐assembly of nanoparticles against the polymer shells as driven by the capillary force during solvent evaporation, producing hollow superstructures. Such a space‐confined assembly process can be well controlled by choice of solvents and their evaporation rates. This general technique provides an open and low‐cost platform for creating hollow superstructures of various inorganic nanoparticles, offering many opportunities for exploring unique applications that can take advantage of the collective properties of the constituent nanoparticles and the permeable nanoshell structures.

Expensive instruments and complicated data processing are often required to discriminate solvents with similar structures and properties. Colorimetric sensors with high selectivity, low cost, and good portability are highly desirable to simplify such detection tasks. Herein, we report the fabrication of a photonic crystal sensor based on the self-assembled resorcinol formaldehyde (RF) hollow spheres to realize colorimetric sensing of polar solvents, including homologs and isomers based on the saturated diffusion time. The diffusion of solvent molecules through the photonic crystal film exhibits a unique three-step diffusion profile accompanied by a dynamic color change, as determined by the physicochemical properties of the solvent molecules and their interactions with the polymer shells, making it possible to accurately identify the solvent type based on the dynamic reflection spectra or visual perception. With its superior selectivity and sensitivity, this single-component colorimetric sensor represents a straightforward tool for convenient solvent detection and identification.

Precise patterning of functional nanoparticles can provide a powerful tool for next-generation macroscale devices. Here, the authors report a reliable nanoprinting technique that can pattern various functional nanoparticles on the substrate with a 200 nm pitch and 10 nm position accuracy, and above the millimeter scale.

Programmable mechanochromic systems hold important roles in designing advanced bionic robots and colorimetric devices. Herein, the authors report the development of magnetic-plasmonic hybrid nanorods that can be integrated into thin polymer films with controlled orientations to display programmable mechanochromism.

Anion exchange membrane water electrolysis (AEMWE) is considered the next generation of green hydrogen production method because it uses low-cost non-noble metal oxide electrocatalyst electrodes and can store high-purity hydrogen under high pressure. However, the commercialization of AEMWE with non-precious metal oxide electrocatalysts is challenging due to low electrocatalytic activity and durability. Overcoming the low kinetics caused by four-electron transfer is vital in addressing the low activity of non-noble metal oxide electrocatalysts for oxygen evolution reaction. This article overviews the synthesis methods and related techniques for various anode electrodes applied to AEMWE systems. We highlight effective strategies that have been developed to improve the performance and durability of the non-precious electrocatalysts and ensure the stable operation of AEMWE, followed by a critical perspective to encourage the development of this technology.

An intermittent frequency synthesizer for fast duty-cycled receivers is presented in this paper. Different from state-of-art techniques which try to eliminate the initial phase error that degrades the intermittent frequency detection, a new frequency detector is proposed to maintain an accurate frequency detection regardless of the initial phase error. Moreover, an averaged fraction division scheme (AFDS) is integrated in the synthesizer to improve the frequency resolution. The frequency synthesizer is implemented and verified by using discrete devices and an FPGA. The measurement results show that the frequency detector provides a frequency detection accuracy of 0.88%, and the synthesizer achieves a frequency resolution of 0.625 MHz when controlled by a duty-cycled signal with a 6-μs period and a 2-μs time duration. The frequency synthesizer can perform an intermittent frequency hopping from 160MHz to 140MHz while requiring a period of 430 μs without disturbing the VCO's oscillation.

The nonradiative conversion of light to heat by plasmonic nanostructures, the so‐called plasmonic photothermal effect, has attracted enormous attention due to their widespread potential applications. Herein, the perspectives on the design and preparation of plasmonic nanostructures for light to heat or photothermal conversion are provided. The general principle of plasmonic photothermal conversion is first introduced, and then, the strategies for improving efficiency are discussed, which is the focus of this field. Then, five typical application types are used, including solar energy harvesting, photothermal actuation, photothermal therapy, laser‐induced color printing, and high‐temperature photothermal devices, to elucidate how to tailor the nanomaterials to meet the requirements of these specific applications. In addition to the photothermal effect, other unique physical and chemical properties are coupled to further explore the application scenarios of plasmonic photothermal materials. Finally, a summary and the perspectives on the directions that may lead to the future development of this exciting field are also given.

This paper presents a driver amplifier with high bandwidth-power efficiency, high capacitor-driving capacity, and low total harmonic distortion (THD). One complementary differential pair composed of self-cascode transistors is incorporated to obtain a full input voltage swing. Flipped voltage follower (FVF) buffers are applied as second stage to drive the last class-AB output stage. Moreover, a dual-loop active-feedback frequency compensation (DLAFC) is presented, which can stabilize the proposed multistage amplifier and keep the dominant pole on high frequency to obtain high-frequency total harmonic distortion (THD) suppression. To achieve a low-frequency phase margin protection (PMP), one left half-plane (LHP) zero is introduced to compensate for the nondominant pole caused by the load capacitor. Meanwhile, two high-frequency LHP zeros are injected to achieve high-frequency phase margin boosting (PMB) and reduce the amplifier’s settling time and integration area. This proposed amplifier is implemented in a standard DBH 0.18 μm 5 V CMOS process, and it achieves over 115-dB DC gain, 150–300 MHz GBW under 0–100 p load capacitors, ultra-high THD2,3 suppression ranges from 100 kHz to 10 MHz under 1–2 V output swing, and over 250 V/μs average slew rate, by only dissipating 12.5 mW at 5 V power supply.

Summary: Advanced oxidation processes (AOPs) based on sulfate radicals (SO4⋅−) suffer from low conversion rate of Fe(III) to Fe(II) and produce a large amount of iron sludge as waste. Herein, we show that by using MoO2 as a cocatalyst, the rate of Fe(III)/Fe(II) cycling in PMS system accelerated significantly, with a reaction rate constant 50 times that of PMS/Fe(II) system. Our results showed outstanding removal efficiency (96%) of L-RhB in 10 min with extremely low concentration of Fe(II) (0.036 mM), outperforming most reported SO4⋅−-based AOPs systems. Surface chemical analysis combined with density functional theory (DFT) calculation demonstrated that both Fe(III)/Fe(II) cycling and PMS activation occurred on the (110) crystal plane of MoO2, whereas the exposed active sites of Mo(IV) on MoO2 surface were responsible for accelerating PMS activation. Considering its performance, and non-toxicity, using MoO2 as a cocatalyst is a promising technique for large-scale practical environmental remediation. : Inorganic Chemistry; Catalysis; Water Resources Engineering Subject Areas: Inorganic Chemistry, Catalysis, Water Resources Engineering

It is highly desirable, while still challenging, to obtain noble metal nanocrystals with custom capping ligands, because their colloidal synthesis relies on specific capping ligands for the shape control while conventional ligand exchange processes suffer from “the strong replaces the weak” limitation, which greatly hinders their applications. Herein, we report a general and effective ligand exchange approach that can replace the native capping ligands of noble metal nanocrystals with virtually any type of ligands, producing flexibly tailored surface properties. The key is to use diethylamine with conveniently switchable binding affinity to the metal surface as an intermediate ligand. As a strong ligand, it in its original form can effectively remove the native ligands; while protonated, it loses its binding affinity and facilitates the adsorption of new ligands, especially weak ones, onto the metal surface. By this means, the irreversible order in the conventional ligand exchange processes could be overcome. The efficacy of the strategy is demonstrated by mutual exchange of the capping ligands among cetyltrimethylammonium, citrate, polyvinylpyrrolidone, and oleylamine. This novel strategy significantly expands our ability to manipulate the surface property of noble metal nanocrystals and extends their applicability to a wide range of fields, particularly biomedical applications.

Smart materials with switchable optical properties may find interesting applications in designing advanced intelligent systems. Herein, the dynamic tuning of optical transmission is reported by controlling the orientation of 1D colloidal assemblies of magnetic nanostructures. Colloidal magnetic nanostructures of Fe3O4, including nanospheres, nanorods, and nanodiscs, are assembled into 1D chains under external magnetic fields. Magnetic tuning of the orientation of the nanochains results in a pronounced contrast in optical transmittance, which is strongly dependent on the size and shape of the primary nanostructures. Contrary to the intuitive expectation, the 1D chains of the nanospheres and nanorods exhibit lower transmittance when they are oriented parallel rather than perpendicular to the incident light, whereas the nanodisc counterpart responds oppositely due to the unique “edge‐to‐edge” assembly mode of the nanodiscs. The dynamic tuning of the optical transmittance through magnetic means is believed to have broad applications in the design of novel switchable optical devices. As an example, the incorporation of orientation‐dependent optical properties of 1D chains into the construction of intelligent polymer films with their transparency sensitive to rotation and bending is demonstrated.

Owing to their unique properties, hollow metal nanocrystals demonstrate greater catalytic promise than their solid counterparts. Here the authors produce hollow and inflated palladium nanocrystals with thin shells via a repeated Kirkendall cavitation process, and demonstrate their activity for formic acid oxidation.

A process-voltage-temperature (PVT)-robust, low power, low noise, and high sensitivity, super-regenerative (SR) receiver is proposed in this paper. To enable high sensitivity and robust-PVT operation, a fast locking phase-locked-loop (PLL) with initial random phase error reduction is proposed to continuously adjust the center frequency deviations of the SR oscillator (SRO) without interrupting the input data stream. Additionally, a concurrent quenching waveform (CQW) technique is devised to improve the SRO sensitivity and its noise performance. The proposed SRO architecture is controlled by two separate biasing branches to extend the sensitivity accumulation (SA) phase and reduce its noise during the SR phase, compared to the conventional optimal quenching waveform (OQW). The proposed SR receiver is implemented at 2.46 GHz center frequency in 180 nm SMIC CMOS technology and achieves better sensitivity, power consumption, noise performance, and PVT immunity compared with existent SR receiver architectures.

Instantaneous control over the orientation of anisotropically shaped plasmonic nanostructures allows for selective excitation of plasmon modes and enables dynamic tuning of the plasmonic properties. Herein we report the synthesis of rod-shaped magnetic/plasmonic core-shell nanocomposite particles and demonstrate the active tuning of their optical property by manipulating their orientation using an external magnetic field. We further design and construct an IR-photoelectric coupling system, which generates an output voltage depending on the extinction property of the measured nanocomposite sample. We employ the device to demonstrate that the nanocomposite particles can serve as units for information encryption when immobilized in a polymer film and additionally when dispersed in solution can be employed as a new type of magnetic-field-direction sensor.

Steelmaking contributes 8% to the total CO2 emissions globally, primarily due to coal-based iron ore reduction. Clean hydrogen-based ironmaking has variable performance because the dominant gas–solid reduction mechanism is set by the defects and pores inside the mm- to nm-sized oxide particles that change significantly as the reaction progresses. While these governing dynamics are essential to establish continuous flow of iron and its ores through reactors, the direct link between agglomeration and chemistry is still contested due to missing measurements. In this work, we directly measure the connection between chemistry and agglomeration in the smallest iron oxides relevant to magnetite ores. Using synthesized spherical 10-nm magnetite particles reacting in H2, we resolve the formation and consumption of wüstite (Fe1-xO)—the step most commonly attributed to whiskering. Using X-ray diffraction, we resolve crystallographic anisotropy in the rate of the initial reaction. Complementary imaging demonstrated how the particles self-assemble, subsequently react, and grow into elongated “whisker” structures. Our insights into how morphologically uniform iron oxide particles react and agglomerate in H2 reduction enable future size-dependent models to effectively describe the multiscale aspects of iron ore reduction. [ABSTRACT FROM AUTHOR]

The article reports an ultrasensitive photoelectrochemical (PEC) sensor for H2S by modifying indium tin oxide (ITO) electrodes with Cd2+-doped amorphous TiO2 hollow spheres.The decreased photocurrent could be attributed to the mismatching bandgap between the amorphous TiO2 and CdS nanoparticles. Enabled by a unique sensitization mechanism, the PEC sensor features excellent performance in a wide linear range, high selectivity and sensitivity, high stability, and low fabrication cost.