Catalytic Metal Foam by Chemical Melting and Sintering of Liquid Metal Nanoparticles

Metal foams are highly sought‐after porous structures for heterogeneous catalysis, which are fabricated by templating, injecting gas, or admixing blowing agents into a metallic melt at high temperatures. They also require additional catalytic material coating. Here, a low‐melting‐point liquid metal is devised for the single‐step formation of catalytic foams in mild aqueous environments. A hybrid catalytic foam fabrication process is presented via simultaneous chemical foaming, melting, and sintering reaction of liquid metal nanoparticles. As a model, nanoparticles of tertiary low‐melting‐point eutectic alloy of indium, bismuth, and tin (Field's metal) are processed with sodium hydrogen carbonate, an environmentally benign blowing agent. The competing endothermic foaming and exothermic sintering reactions are triggered by an aqueous acidic bath. The overall foaming process occurs at a localized temperature above 200 °C, producing submicron‐ to micron‐sized open‐cell pore foams with conductive cores and semiconducting surface decorations. The catalytic properties of the metal foams are explored for a range of applications including photo‐electrocatalysis, bacteria electrofiltration, and CO₂ electroconversion. In particular, the Field's metal‐based foams show exceptional CO₂ electrochemical conversion performance at low applied voltages. The facile process presented here can be extended to other low‐temperature post transition and transition metal alloys.     

Liquid Polydimethylsiloxane Grafting to Enable Dendrite‐Free Li Plating for Highly Reversible Li‐Metal Batteries

Li‐metal is considered as the most promising anode material to advance the development of next‐generation energy storage devices owing to its unparalleled theoretical specific capacity and extremely low redox electrochemical potential. However, safety concerns and poor cycling retention of Li‐metal batteries (LMBs) caused by uncontrolled Li dendrite growth still limit their broad application. Herein, liquid polydimethylsiloxane (PDMS) terminated by –OCH₃ groups is proposed as a graftable additive to reinforce the anode dendrite suppression for LMBs. Such a grafting triggers the formation of a conformal hybrid solid electrolyte interphase (SEI) with increased fractions of LiF and Li–Si–O‐based moieties, which serve as a rigid barrier and ionic conductor for uniform Li‐ion flow and Li‐mass deposition. The grafting protected anode endows Li/Li symmetric cells with a long lifetime over 1800 h with a much smaller voltage gap (≈25 mV) between Li plating and stripping, than the naked anode. The coulombic efficiency values for Li/Cu asymmetric cells in carbonate electrolyte can reach up to 97% even at a high current density of 3 mA cm^?2 or high capacity up to 4 mAh cm^?2. The liquid PDMS additive shows advantage over solid siloxane additives with poor grafting ability in terms of Li surface compaction and SEI stabilization.     

Multifunctional Liquid-Free Ionic Conductive Elastomer Fabricated by Liquid Metal Induced Polymerization

Novel liquid-free ionic conductive elastomers are fabricated by the polymerization of acrylic acid (AA) in polymerizable deep eutectic solvent (PDES). Liquid metal (LM) nanodroplets are used to initiate and further cross-link polyacrylic acid (PAA) chains into a liquid-free polymeric network without any extra initiators and cross-linkers. The resulting liquid-free ionic conductive elastomers exhibit high transparency (94.1%), ultra-stretchability (2600%), and autonomous self-healing. Spin trapping electron paramagnetic resonance and dye fading experiments reveal the generation of free radicals. UV–visible spectrometry and viscosity tests demonstrate the cross-linking effect of Ga³⁺. The gelation time is much shorter than that of the conventional ammonium persulfate thermal initiation process. Furthermore, this liquid-free polymer material is intrinsically resistant to freezing and drying, enabling it to operate under harsh conditions. In consideration of transparency, self-healing, ultra-stretchability, moldability, and sensory features, the resulting elastomeric conductor may hold promise for industrial applications in wearable devices, force mapping, and flexible electroluminescent devices.     

金属粉末的直接选区激光烧结温度场数值模拟

金属粉末的直接选区激光烧结(DMLS)过程中存在着相变潜热,在考虑相变潜热的作用下,基于金属粉末烧结成形建立了一种三维的瞬态有限元模型,该模型还考虑了随温度变化而变化的热传导、自然对流和辐射的影响。采用ANSYS参数化设计语言处理移动热源,用焓处理相变潜热的影响。以25号钢粉末为烧结材料进行了数值模拟,模拟结果表明：激光烧结过程中,在光斑中心的前端存在着极大的温度梯度;光斑中心的温度高于金属粉末的熔点,烧结过程中存在液相。     

Enhancing Water Oxidation Catalysis by Controlling Metal Cation Distribution in Layered Double Hydroxides

The sluggish kinetics of the oxygen evolution reaction (OER), the limiting step of the electrochemical water splitting process, hinders the eventual commercialization of this important renewable energy strategy. Hence, the development of efficient electrocatalysts for this reaction is crucial. Multi-metal-based (hydr)oxides are promising OER electrocatalysts because the electronic interactions between multiple constituent metal cations can potentially enhance electrochemical performances. However, complex compositions may not always lead to positive synergistic effects. The appropriate distribution of the cations is also critical. However, the high dispersibility of cations in these hydroxides renders the control of their distribution challenging. Herein, an approach is reported to control the metal cation distribution in layered double hydroxides (LDHs) to improve their OER performances. Restacking of exfoliated NiFe and CoAl LDH nanosheets leads to electrochemical synergistic effects between different nanosheets. As far as it is known, the restacked LDH described herein exhibits the lowest overpotential (224 mV) and Tafel slope (34.26 mV dec⁻¹) among reported powder-type (hydr)oxide and alloy OER electrocatalysts with more than three different metal cations. Thus, a new design approach is suggested to enhance the electrochemical performances of LDHs.     

Durable Li2CN2 Solid Electrolyte Interphase Wired by Carbon Nanodomains via In Situ Interface Lithiation to Enable Long-Cycling Li Metal Batteries

Lithium metal batteries (LMBs) are becoming the promising candidate of high-energy storage systems. However, the fragile natural solid electrolyte interphase (SEI) cannot retard the Li dendrite growth at anode, which will cause the low coulombic efficiency (CE) of Li plating/stripping and safety hazards in LMBs. Here, an in situ construction strategy of novel artificial SEI consisting of Li₂CN₂ ionic conductor wired by carbon nanodomains via dicyandiamide solution reaction method on Li metal surface is proposed. This lithiophilic Li₂CN₂ has the higher anti-reduction stability and longer critical length for Li dendrite, showing the excellent dendrite suppressing ability. The wired carbon domains promote the electron connection and charge homogenization in SEI, leading to the uniform Li nucleation around Li₂CN₂/C grains with enhanced interface kinetics and reduced polarization. This dual conductive Li₂CN₂/C network enables the durable preservation of high CE and low voltage hysteresis during Li plating/stripping, endowing LiNi_0.8Mn_0.1Co_0.1O₂/Li cells with ultralong cycling life exceeding 1000 cycles at high rate. The cycling stabilization effect is also remarkable even under thin Li anode and high-loading cathode conditions. This study provides a solution to robust SEI configuration of high conductivity via in situ interface lithiation reaction for high-performance LMBs.     

红外测温对圆筒设备内部温度及内壁缺陷的定量检测

对于稳定传热的长圆筒形设备,利用红外测温技术获取设备外部信息,计算得出设备 内部的温度分布或内壁缺陷,为设备内部运行状态的实时监测提供理论依据。