Enhanced active site extraction from perovskite LaCoO_(3) using encapsulated PdO for efficient CO_(2) methanation

The extraction of metallic nanoparticles from perovskite-type oxides(ABO_(3)) under mild reducing conditions is a novel way to prepare well-dispersed supported catalysts(B/AOd). Herein, we found that the encapsulated PdO in perovskite LaCoO_3(PdO@LaCoO_3) could facilitate the phase transformation of the perovskite structure at a low temperature owing to both strong H2 spillover of Pd and intimate interaction between the encapsulated PdO and LaCoO_(3). The pure LaCoO_(3) without PdO was relatively inert to CO_(2) hydrogenation(CO_(2) conversion <4%). In contrast, PdO@LaCoO_(3) exhibited excellent CO_(2) methanation performance with 62.3% CO_(2) conversion and >99% CH4 selectivity. The characterization results demonstrated that the catalytically active Co2 C was in-situ formed by carburization of the extracted Co0 during CO_(2) methanation for the PdO@LaCoO_(3) sample. Whereas, the LaCoO_(3) with surface supported PdO(PdO/LaCoO_(3)) showed a weak interaction and remained a perovskite structure with few Co_(2)C active centers after the catalytic reaction, which was similar to the parent LaCoO_(3). Accordingly, the PdO/LaCoO_(3) showed an inferior catalytic performance with 31.8% CO_(2) conversion and 87.4% CH_(4) selectivity. Therefore, the designed encapsulation structure of PdO within perovskite is critical to extract metallic NPs from perovskite-type oxides, which has the potential to prepare other integrated nanocatalysts based on perovskite-type oxides.

Recent development of transient electronics

Transient electronics are an emerging class of electronics with the unique characteristic to completely dissolve within a programmed period of time. Since no harmful byproducts are released, these electronics can be used in the human body as a diagnostic tool, for instance, or they can be used as environmentally friendly alternatives to existing electronics which disintegrate when exposed to water. Thus, the most crucial aspect of transient electronics is their ability to disintegrate in a practical manner and a review of the literature on this topic is essential for understanding the current capabilities of transient electronics and areas of future research. In the past, only partial dissolution of transient electronics was possible, however, total dissolution has been achieved with a recent discovery that silicon nanomembrane undergoes hydrolysis. The use of single- and multi-layered structures has also been explored as a way to extend the lifetime of the electronics. Analytical models have been developed to study the dissolution of various functional materials as well as the devices constructed from this set of functional materials and these models prove to be useful in the design of the transient electronics.

Ultra-thick,dense dual-encapsulated Sb anode architecture with conductively elastic networks promises potassium-ion batteries with high areal and volumetric capacities

Ultra-thick,dense alloy-type anodes are promising for achieving large areal and volumetric performance in potassium-ion batteries(PIBs),but severe volume expansion as well as sluggish ion and electron diffusion kinetics heavily impede their widespread application.Herein,we design highly dense(3.1 g cm^(-3))Ti_(3)C_(2)T_(x) MXene and graphene dual-encapsulated nano-Sb monolith architectures(HD-Sb@Ti_(3)C_(2)T_(x)-G)with high-conductivity elastic networks(1560 S m^(-1))and compact dually encapsulated structures,which exhibit a large volumetric capacity of 1780.2 mAh cm^(-3)(gravimetric capacity:565.0 mAh g^(-1)),a long-term stable lifespan of 500 cycles with 82%retention,and a large areal capacity of 8.6 mAh cm^(-2)(loading:31 mg cm^(-2))in PIBs.Using ex-situ SEM,in-situ TEM,kinetic investigations,and theoretical calculations,we reveal that the excellent areal and volumetric performance mechanism stems from the three dimensional(3D)high-conductivity elastic networks and the dualencapsulated Sb architecture of Ti_(3)C_(2)T_(x) and graphene;these effectively mitigate against volume expansion and the pulverization of Sb,offering good electrolyte penetration and rapid ionic/electronic transmission.Ti_(3)C_(2)T_(x) also decreases the Kþdiffusion energy barrier,and the ultra-thick compact electrode ensures volumetric and areal performance.These findings provide a feasible strategy for fabricating ultra-thick,dense alloy-type electrodes to achieve high areal and volumetric capacity energy storage via highly-dense,dual-encapsulated architectures with conductive elastic networks.

Fabrication and catalytic performance of meso-ZSM-5 zeolite encapsulated ferric oxide nanoparticles for phenol hydroxylation

An encapsulation-structured Fe_(2)O_(3)@mesoZSM-5(Fe@MZ5)was fabricated by confining Fe_(2)O_(3) nanoparticles(ca.4 nm)within the ordered mesopores of hierarchical ZSM-5 zeolite(meso-ZSM-5),with ferric oleate and amphiphilic organosilane as the iron source and meso-porogen,respectively.For comparison,catalysts with Fe_(2)O_(3)(ca.12 nm)encapsulated in intra-crystal holes of meso-ZSM-5 and with MCM-41 or ZSM-5 phase as the shell were also prepared via sequential desilication and recrystallization at different pH values and temperatures.Catalytic phenol hydroxylation performance of the as-prepared catalysts using H_(2)O_(2) as oxidant was compared.Among the encapsulation-structured catalysts,Fe@MZ5 showed the highest phenol conversion and hydroquinone selectivity,which were enhanced by two times compared to the Fe-oxide impregnated ZSM-5(Fe/Z5).Moreover,the Fe-leaching amount of Fe@MZ5 was only 3% of that for Fe/Z5.The influence of reaction parameters,reusability,and ·OH scavenging ability of the catalysts were also investigated.Based on the above results,the structure-performance relationship of these new catalysts was preliminarily described.