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Wet-chemistry synthesis of two-dimensional Pt- and Pd-based intermetallic electrocatalysts for a wide range of applications in fuel cells.

Coral ball-like MoS2/N–C nanohybrids were designed and prepared purposely by a wet-chemistry approach with subsequent annealing as superior electrode materials for SIBs and PIBs.

Chiral metal halide perovskites with intrinsic asymmetric structures have drawn increased research interest for the application of second-order nonlinear optics (NLO). However, designing chiral perovskites with the features of a large NLO coefficient, high laser-induced damage thresholds (LDT), and environmental friendliness remains a major challenge. Herein, we have synthesized two chiral hybrid bismuth halides: (R/S-MBA)

The development of cost-effective and high-performance electrocatalysts has been increasingly studied to mitigate upcoming energy and environmental challenges. Amorphization and heterointerface engineering have played significant roles in the rational design of electrocatalysts and modulation of their electrocatalytic activities. However, the synergistic effect between amorphization and heterointerfaces has been scarcely reported. As a proof-of-concept attempt, we develop amorphous FeMo (a-FeMo) electrocatalysts with an abundance of heterointerfaces that are composed of amorphous components and evaluate their electrocatalytic performances toward the nitrogen reduction reaction and oxygen evolution reaction (OER). Benefitting from the synergistic effect between the amorphous nature of the a-FeMo electro-catalysts, which offer a high density of active sites, and significant electron redistribution at the heterointerfaces, the electrocatalysts exhibit a high Faradaic efficiency of 29.15%, an elevated yield rate of $$71.78\,{\rm{\mu}}{{\rm{g}}_{{\rm{N}}{{\rm{H}}_3}}}\,{\rm{m}}{{\rm{g}}_{{\rm{cat}}{\rm{.}}}}^{- 1}{{\rm{h}}^{- 1}}$$ with long-term stability at a potential of −0.1 V vs. reversible hydrogen electrode and excellent electrocatalytic activity toward the OER. This study provides a promising and effective method for the rational design of low-cost heterogeneous catalysts with desirable efficiency, selectivity, and stability.

In recent years, intermetallic nanocrystals (IMNCs) have attracted extensive attention in the field of electrocatalysis. However, precise control over the size, shape, composition, structure, and exposed crystal facet of IMNCs seems to be a challenge to the traditional method of high-temperature annealing although these parameters have a significant effect on the electrocatalytic performance. Controllable synthesis of IMNCs by the wet chemistry method in the liquid phase shows great potential compared with the traditional high-temperature annealing method. In this Review, we attempt to summarize the preparation of IMNCs by the seed-mediated synthesis in the liquid phase, as well as their applications in electrocatalytic reduction reactions. Several representative examples are purposely selected for highlighting the huge potential of the seed-mediated synthesis approach in chemical synthesis. Specifically, we personally perceive the seed-mediated synthesis approach as a promising tool in the future for precise control over the size, shape, composition, structure, and exposed crystal facet of IMNCs.

As a potential energy carrier, hydrogen has surged up the priority list as part of broader decarbonization efforts and strategies to build or acquire clean energy economies. Driven by renewable electricity, electrochemical water splitting (WS) promises an ideal long-term, low-carbon way to produce hydrogen, with the ability to tackle various critical energy challenges. To improve the efficiency of electrocatalytic water splitting, electrocatalysts with enhanced conductivity, more exposed active sites, and high intrinsic activity are crucial for decreasing the energy gap for the rate-determining step (RDS) and subsequently improving the conversion efficiency. The incorporation of multidimensional imperfections has been demonstrated to be efficient for modulating the electron distribution and speeding up the electrocatalysis kinetics during electrocatalytic processes and this is now attracting ever-increasing attention. Herein, in this review, we summarize recent progress relating to the regulation of electrical behavior and electron distributions for the optimization of electrocatalytic water-splitting performance via defect engineering. With an emphasis on the beneficial aspects of the hydrogen economy and an in-depth understanding of electron redistribution caused by defect effects, we offer a comprehensive summary of the progress made in the last three to five years. Finally, we also offer future perspectives on the challenges and opportunities relating to water-splitting electrocatalysts in this attractive field.

Rational design of catalytic sites to activate the inert N≡N bond is of paramount importance to advance N2 electroreduction. Here, guided by the theoretical predictions, we construct a NiFe layered double hydroxide (NiFe-LDH) nanosheet catalyst with a high density of electron-deficient sites, which were achieved by introducing oxygen vacancies in NiFe-LDH. Density functional theory calculations indicate that the electron-deficient sites show a much lower energy barrier (0.76 eV) for the potential determining step compared with that of the pristine NiFe-LDH (2.02 eV). Benefiting from this, the NiFe-LDH with oxygen vacancies exhibits the greatly improved electrocatalytic activity, presenting a high NH3 yield rate of 19.44 µg·h−1·mgcat−1, Faradaic efficiency of 19.41% at −0.20 V vs. reversible hydrogen electrode (RHE) in 0.1 M KOH electrolyte, as well as the outstanding stability. The present work not only provides an active electrocatalyst toward N2 reduction but also offers a facile strategy to boost the N2 reduction.

Low-dimensional organic-inorganic hybrid perovskites have demonstrated to be promising semiconductor materials due to their unique optoelectronic properties, however, the controllable growth of high-quality ultrathin 2D perovskites with large lateral dimension still faces great challenges. Herein, we report the controllable growth of large-scale ultrathin 2D (C6H5(CH2)3NH3)3Pb2I7 ((PPA)3Pb2I7) perovskite nanosheets (NSs) using a facile antisolvent-assisted crystallization approach under mild condition. As a result, the well-defined regular-shaped (PPA)3Pb2I7 NSs, with the largest lateral size over 100 μm, have been successfully synthesized, which is more than several ten times larger than that of other 2D perovskite NSs previously reported. Moreover, the thickness of the achieved 2D perovskite NSs can be well-tuned by altering the concentration of the precursor solution, with the smallest thickness down to ∼4.7 nm. More importantly, the photodetectors based on the high-quality (PPA)3Pb2I7 perovskites exhibit fascinating performance, including an extremely low dark current (∼1.5 pA), fast response/recovery rate (∼850/780 μs), and high detectivity (∼1.2 × 1010 Jones). This work provides a simple and promising strategy to controllably grow large-scale and ultrathin 2D perovskite NSs for low-cost and high-performance optoelectronic devices.

Atomically ordered intermetallic nanocrystals have been extensively explored in electrocatalysis due to their outstanding catalytic performances and excellent stabilities. However, controllable synthesis of intermetallic nanocrystals in terms of their size and structure remains a grand challenge due to the generally involved high-temperature thermal annealing synthetic method, largely hindering the optimization of their catalytic properties. Herein, we report a versatile approach to the synthesis of atomically ordered Pd3Pb multiply twinned intermetallic nanowire networks (MT-IM-NNs) with a tunable diameter and microstructure. The use of preformed Pd seeds, which were converted to a Pd3Pb intermetallic phase via the diffusion of Pb atoms into the seeds, as well as an oriented attachment growth mode, accounted for the formation of such a unique structure. Importantly, the diameter and microstructure of Pd3Pb MT-IM-NNs could be engineered by controlling the size and type of Pd seeds. In addition, the Pd3Pb multiply twinned intermetallic porous nanowire networks exhibited a high faradaic efficiency of 21.46% and an NH3 yield rate of 18.2 μg h−1 mgcat−1 at −0.2 V vs. the reversible hydrogen electrode toward N2 electroreduction.

NiFe layered double hydroxides (LDHs) have received widespread attention due to their unique structures and inherent electrocatalytic activity towards the oxygen evolution reaction (OER). Extensive studies have been reported to further improve the electrocatalytic activity of NiFe-LDHs via various strategies. However, controlling the degree of amorphization and stabilizing the amorphous zone during the electrocatalytic process are still challenging. Here, we report a facile method to synthesize a space-confined amorphous NiFe-LDH (SCA-NiFe-LDH) by selectively etching the surfaces of electrocatalysts. Due to the successful anchoring of amorphous zones onto the basal planes of the two-dimensional NiFe-LDH, the optimized SCA-NiFe-LDH exhibits high electrocatalytic activity with a low overpotential of 190 mV at 10 mA cm-2, a Tafel slope of 31 mV dec-1 and excellent long-term stability. The substantially enhanced OER performance is attributed to the increased amount of active sites and the modified electronic structure of NiFe-LDH after amorphization.

A room-temperature NO2 gas sensor with excellent performances is fabricated using an MAPbI3 (MA = CH3NH3+) thin film. It presents a high response even under extremely low NO2 concentrations. Its average response and recovery times are only ∼5 s and ∼25 s at room temperature, respectively, exhibiting its quick-responsive character. In addition, the MAPbI3-based NO2 sensor exhibits good selectivity. Interestingly, the sensitivity of the MAPbI3-based NO2 sensor is strikingly improved under high-pressure gas conditions. This phenomenon can be used for the online monitoring of chemical reaction processes and in situ detection of trace-level gas impurities under high-pressure conditions. Furthermore, based on theoretical calculations, a simple model is proposed to illustrate the corresponding gas-sensing mechanism.

Development of sodium-ion batteries (SIBs) and hydrogen evolution reaction (HER) technologies to achieve electrochemical energy storage and conversion has attracted intensive interest. MoS2 is bifunctionally active towards both SIBs and HER. However, poor electrical conductivity, limited active sites and sluggish ion diffusion kinetics generally give rise to rapid capacity fading, poor cycling stability, and low electrocatalytic activity when used as electrode materials. Herein we designed hierarchical MoS2/m-C@a-C@Ti3C2 nanohybrids as electrode materials for SIBs and HER. The nanohybrids are fabricated by vertically anchoring the few-atomic-layered MoS2 nanosheets, with alternated intercalation of carbon monolayers, on the both sides of carbon-stabilized Ti3C2 substrate. They afford 3D interconnected conductive networks, expanded interlayer distance and strong interfacial coupling, enabling fast charge transfer, abundant active sites, high structural stability and ion diffusion kinetics. Benefited from the synergistic effects, the nanohybrids exhibit ultra-long cycling life of 2000 cycles with high capacities and slow capacity loss per cycle at 2 and 5 A g−1 for Na+ storage. They also present high HER activity in both alkaline and acidic solutions (overpotential: 110 and 93 mV (vs. RHE) at 10 mA cm−2). These superior properties demonstrate the great promise of this designed strategy for energy storage and conversion.

Compact graphene film electrodes with a high ion-accessible surface area have the promising potential to realize high-density electrochemical energy storage (or high volumetric capacitance), which is vital for the development of flexible, portable, and wearable energy storage devices. Here, a novel, ultrafast strategy for stitching graphene sheets into films, in which p-phenylenediamine (PPD) molecules are uniformly intercalated between the graphene sheets, is simply constructed at the ethanol/water interface. Due to uniformly interlayer spacing (∼1.1 nm), good wettability, and an interconnected ion transport channel, the binder-free PPD–graphene film with a high packing density (1.55 g cm–3) delivers an ultrahigh volumetric capacitance (711 F cm–3 at a current density of 0.5 A g–1), high rate performance, high power and energy densities, and excellent cycling stability in aqueous electrolytes. This interfacial stitching strategy holds new promise for the future design of enhanced electrochemical energy-s...

In perovskite–TiO2 composite optoelectronic devices, a large grain size, a high percentage of {001} facets, TiO2 nanocrystals with high crystallinity, and good interconnectivity between both TiO2 and perovskite particles are crucial for the excellent performance of a hybrid photodetector. In this work, a high pressure hydrothermal method was developed to synthesize highly crystalline ultrathin (2–3 nm) TiO2 nanosheets bound with a high percentage of {001} facets. When these TiO2 nanosheets were utilized in the fabrication of perovskite–TiO2 composite photodetectors, a strikingly increased responsivity and detectivity were achieved. Furthermore, when the films were subjected to high pressure thermal treatment, both the particle size and the uniformity of the composite films greatly increased, resulting in a better performance of the hybrid photodetectors.

Carbon capture, utilization, and storage (CCUS) is an important emissions reduction technology that can be deployed in the industrial sector and in the power generation. By converting the CO2 in the atmosphere into value-added hydrocarbons with high energy density and ease of transportation and storage, CO2 utilization has witnessed a sharp rise in the amount of public and private spending on R&D programs and projects. Copper has been proved as the only known electrocatalyst that can catalyze the CO2 into hydrocarbons with adequate efficiency and selectivity. In this review, we will begin with an introduction of some background to the electrochemical CO2 reduction reactions (ECR) process. Followed by a discussion of the world’s energy status, we then focus on the advances for the optimization of the Cu-based electrocatalysts that generate multi-carbon products to meet the requirements of the industry from the point-view of electrolyzer design, electrocatalysts design and electrolyte design. Afterwards, we highlight the in-depth understanding of the electrocatalytic process combining theoretical methods and in-situ/operando experimental approaches. Finally, we present the challenges by discussing how they can be overcome to achieve a carbon-neutral economy.

Efficient removal of heat via thermal interface materials has become one of the most critical challenges in the development of modern microelectronic devices. However, traditional polymer composites present limited thermal conductivity even when highly loaded with highly thermally conductive fillers due to the lack of efficient heat transfer channels. In this work, vertically aligned and interconnected graphene networks are first used as the filler, which is prepared by a controlled three-step procedure: formation of graphene oxide liquid crystals, oriented freeze casting, and high-temperature annealing reduction under Ar. The obtained composite, at an ultralow graphene loading of 0.92 vol %, exhibits a high thermal conductivity (2.13 W m–1 K–1) that is equivalent to a dramatic enhancement of 1231% compared to the pure matrix. Furthermore, the composite also presents a much reduced coefficient of thermal expansion (∼37.4 ppm K–1) and increased glass transition temperature (135.4 °C). This strategy provide...

Conflicts between the limited energy resources and the continuingly growing demand of the industry accompanied by worsening climate change have pushed the development of energy storage and conversion devices to the center of the research society. Electrocatalysis, which converts chemical energy and electricity to one another, has emerged as a potential solution for providing affordable clean energy and alleviating the environmental crisis. Defects with zero to three dimensions, which can intrinsically influence the electronic structure of the electrocatalysts and its interaction with the surrounding environment, has made the rational design and preparation of electrocatalysts with high activity, long-term stability and acceptable Faradaic efficiency be readily guaranteed. Here, we review the significant role of the defects in selected electrocatalytic processes based on the understanding of the link between the physics and chemistry of the defects. After a background introduction, we give a brief discussion of the formation process of the defects, along with the emerging preparation methods to generate imperfections in the electrocatalysts. Furthermore, a basic-theory-and-practice-combined introduction of the advanced characterization methods for the identification and analysis of defects will be presented. Next, we focus on the recent progress that has been achieved in developing efficient defect-featured electrocatalysts in a wide range of electrocatalytic processes. Finally, we conclude the challenges and opportunities in this promising and thriving field from our perspective.

Optimizing the activity of layered molybdenum disulfide (MoS2) toward hydrogen evolution reaction (HER) process is generally achieved by improving the electrical transport, intrinsic activity, and/or the number of active sites. However, simultaneously coupling these factors to achieve remarkable MoS2-based electrocatalysts has been seldom reported. Herein, we report a facile approach to the defect-rich one-dimensional MoS2 hierarchical architecture (1D-DRHA MoS2), which synergistically integrate the advantageous structural features of rich defects and one-dimensional hierarchal morphology. Toward HER process, the 1D-DRHA MoS2 electrocatalyst exhibited an overpotential of 119 mV at 10 mA cm−2, a Tafel slope of 50.7 mV dec-1, accompanied by an excellent stability. Notably, the activity is competitive to the state-of-the-art MoS2-based electrocatalysts for HER. The combination of experimental evidences and density functional theory calculations demonstrated the incorporation of rich defects and one-dimensional hierarchical structure improved electric conductivity, intrinsic activity, and active sites, which together accounted for the boosted HER performance.

An 850 nm monolithically integrated optical receiver front end has been simulated by ATLAS and developed based on 0.5 μm GaAs PHEMT process, which comprises a metal-semiconductor-metal (MSM) photodetector and a distributed amplifier.The output eye diagrams for 2.5 Gb/s and 5Gb/s NRZ pseudorandom binary sequence are attained. Compared to the characteristics of actual device, this contribution details a simulation strategy for accurate prediction of the unilluminated performances of the devices.

An adaptive optical system has been built for improving optical beam quality in a new inertial confinement fusion (ICF) system. This system is designed to compensate the static and dynamic wavefront errors in the laser generator and amplifier by pre-compensation manner, which includes a 45-channel deformable mirror, two Shack-Hartmann wavefront sensors with 10x10 sub-apertures, a 45-channel high voltage amplifier and a wavefront control computer. Preliminary principle experiment has been done and the experimental results are reported.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.