Search

Ultra-stable Zn-organic frameworks with controllable inverse adsorption separation of C2H2/CO2 demonstrate extraordinary CO2-preferred selectivity and a remarkable productivity of C2H2 with an extra-high purity of more than 99.9% from the CO2/C2H2 (1/99) mixture.

A two-dimensional (2D) MOFs transformation strategy was introduced to synthesize FeNi layered double hydroxides (FeNi LDHs) in NaBH4 solution, which show excellent OER catalytic activity in alkaline media.

Holey CoOOH nanosheets (CoOOH HNSs) are easily synthesized by a successive coordination–oxidation–hydrolysis strategy. The CoOOH HNSs possess a large surface area, numerous pores, and substantial edge atoms with excellent electroactivity towards the oxygen evolution reaction in alkaline solution. The overpotential of 305 mV at 10 mA cm−2 for the CoOOH HNSs exceeds that of most monometallic Co-based electrocatalysts.

The cathodic oxygen reduction reaction (ORR) is a key half-reaction for direct methanol fuel cells (DMFCs). Enhancing the electroactivity and selectivity of cathodic Pt-based ORR electrocatalysts is pivotal for accelerating the commercialization of DMFCs because of the scarcity of Pt metal and the inherent electroactivity of Pt-based electrocatalysts towards the methanol electrooxidation reaction. Herein, highly dispersed carbon nanobowl (CNBs) supported 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid (BmimBF4) functionalized Pt1Rh1 alloy nanocrystal nanohybrids (Pt1Rh1@BmimBF4/CNBs) are successfully synthesized by reducing mixed BmimBF4-PtII and BmimBF4-RhIII complex precipitates with NaBH4 solution. During the reduction process, PtRh alloy nanocrystals are simultaneously functionalized by BmimBF4 because of the strong N–metal interaction. Pt1Rh1@BmimBF4/CNBs nanohybrids with the optimal chemical composition reveal significantly enhanced ORR electroactivity and fascinating ORR selectivity (i.e., methanol tolerance) compared to Pt1Rh1/CNBs nanohybrids without BmimBF4 because of the carrier effect, alloy effect, and particular metal–organic interface.

The controllable synthesis of highly stable porous metal–organic frameworks (MOFs) with targeted functions is urgently needed but still challenging up to now. In this work, we report the latest achievement in our continuous quest for robust 9-connected (9-c) MOFs based on [M3(O/OH)(COO)6(pyridine)3] building blocks. Different from the reported nets (ncb, xmz and pacs-MOFs) constructed from integrated or separated carboxylate and pyridine ligands, our metal–organic linker (MOL) strategy led to the discovery of six fascinating 9-c MOFs (SNNU-51–56) showing two types of completely new topological nets generated by cis, trans-coordination isomerism. As expected from highly connected architectures and the absence of open metal sites, all these MOFs show high thermal and moisture stability. They can even retain their frameworks after being treated at different pH values for 24 h. Furthermore, SNNU-51–56 not only inherit the excellent gas uptake performance of robust 9-c MOFs, but also exhibit extremely high CH4 separation from CO2, C2H2 and C2H4. Together with robust frameworks, the effective inner-cluster redox process in [M3(OH)(COO)6(pyridine)3] (M = Fe, Co and Ni) units makes SNNU-51–56 high-performance electrochemical pseudocapacitor materials. The asymmetric supercapacitor (ASC) fabricated with the SNNU-52 positive electrode and activated carbon (AC) negative electrode can be reversibly charged/discharged in a working voltage range of 0–1.6 V in 2 M KOH aqueous electrolyte for application in practical energy storage devices, and two serially connected ASCs can continuously light a light emitting diode. In all, greater control over the MOF structure, excellent thermal and chemical stability, and superb metal compatibility make [M3(O/OH)(COO)6(pyridine)3] clusters an ideal building block to design multifunctional MOF materials in the future.

As an alternative pathway for present nitrogen fixation methods, the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions represents an attractive approach for sustainable and economic development of chemistry and biology. In this work, we synthesize bimetallic RhCu ultrathin nanoflake nanoaggregates (RhCu-BUNNs) with atomic thickness by a facile hydrothermal method. For the NRR, bimetallic RhCu-BUNNs exhibit better electrocatalytic activity than monometallic Rh ultrathin nanoflake nanoaggregates (Rh-UNNs) because the introduction of Cu can effectively weaken the competitive hydrogen evolution reaction (HER), which can achieve a high NH3 yield rate (95.06 μg h−1 mgcat−1) at −0.2 V potential. Density functional theory (DFT) calculations suggest that the introduction of Cu can effectively lower the energy demand in the *NN reductive process, resulting in NRR activity enhancement. Meanwhile, RhCu-BUNNs also show excellent electrocatalytic activity and selectivity for the glycerol oxidation reaction (GOR). For the electrochemical NH3 production, the sluggish anodic oxygen evolution reaction (OER) increases the overall electrolysis voltage. Herein, we replace the anodic OER with the GOR to assist the NRR using a bifunctional RhCu-BUNN electrocatalyst. Specifically, only 1.2 V whole voltage is required for electrochemical NH3 production in the presence of glycerol, accompanied by the generation of valuable glyceraldehyde at the anode. This work may provide a promising pathway to obtain both NH3 and valuable organic chemicals with high efficiency and low cost.

Developing an easy-to-expand synthetic method for nanostructures is highly desired, which will help in investigating the effect of the type and content of the extended component on catalytic performance. Based on original Au nanowires (NWs), we design a two-step interface control strategy to synthesize a series of bimetallic AuPt NWs and trimetallic AuPtRh NWs for the formic acid oxidation reaction (FAOR). By controlling the proportion of Au and Pt, a Au/Pt interface can achieve a AuPt alloy structure, which makes Au6Pt1/C show a complete direct dehydrogenation pathway for the FAOR. The further design and fabrication of an advanced Au/Pt/Rh interface are proved to be more active than the Au/Pt interface for the FAOR. The mechanism analysis and experimental results demonstrate that Rh atoms on the Au/Pt/Rh interface can provide active hydroxyl species, so that the adsorption of formate and the desorption of generated hydrogen species are promoted at Pt atoms on the Au/Pt/Rh interface. Consequently, Au6Pt1Rh0.5/C electrocatalysts exhibit excellent mass activity (8.05 A mgPt−1) and specific activity (14.3 mA cm−2) for the FAOR, which exceed those of most of the reported Pt-based or Pd-based electrocatalysts.

Proton-coupled electrocatalytic reactions, such as the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) in acidic media, are very important half-reactions of fuel cells and water electrolysis. Aiming at increasing the interfacial proton concentration to improve the ORR/HER activity, we synthesize PdNi alloy nanostructures (PdNi-ANSs)–polyethyleneimine (PEI) inorganic–organic nanocomposites (PdNi-ANSs@PEI) by a PEI assisted cyanogel-reduction strategy. Various physical characterization techniques show that PdNi-ANSs are successfully functionalized by the PEI polymer during the synthesis of PdNi-ANSs@PEI because of the N–Pd interaction. Thanks to the increased interfacial proton concentration caused by the protonation of amine groups at PEI in acidic media, the molecular weight optimized PdNi-ANSs@PEI exhibit enhanced ORR/HER activity compared to PdNi-ANSs without PEI and commercial electrocatalysts, which indicates that the electrocatalytic activity of metal nanostructures can be remarkably improved by reasonable interface design.

Graphene-supported precious metal nanoparticle hybrids have received extensive attention in recent years because of the outstanding physical and chemical properties of graphene. In this work, we synthesize high-quality reduced graphene oxide (RGO) supported monodispersed Pt nanocrystal (Pt/RGO) hybrids with the assistance of polyethyleneimine (PEI), in which PEI serves as a multi-functional molecule for the coordination with K2PtCl4, anchorage of PtII precursors on the graphene oxide surface, and chemical functionalization of Pt nanocrystals. Then, we investigate in detail the effect of the molecular weight of PEI on the electrocatalytic activity of the resultant Pt/RGO hybrids for the formic acid oxidation reaction (FAOR). Electrochemical measurements show that PEI with high molecular weight (Mw = 10 000) between the two RGO sheets limits seriously the access of electrolytes to the Pt sites. In contrast, PEI with low molecular weight (Mw = 600) between the two RGO sheets allows electrolytes to access freely the Pt sites, and the resultant Pt/RGO hybrids show enhanced electrocatalytic activity and stability for the FAOR compared to the commercial Pt/C electrocatalyst due to the ensemble effect.