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We have developed a metastable fcc-RuW toward highly efficient alkaline hydrogen oxidation. The optimized binding strength of intermediates by tailored electronic structure and phase engineering results in the enhanced performance.

Ruthenium oxide-based electrocatalysts have been regarded as promising alternatives to the state-of-the-art Iridium oxide (IrO2) towards acidic oxygen evolution reaction (OER). However, their practical applications of proton exchange membrane water electrolyzer (PEMWE) are severely limited by the lack of efficient strategy to balance the seesaw relation between stability and activity of ruthenium oxide (RuO2)-based catalysts. Herein, we report that both the activity and stability of RuO2can be significantly boosted though bismuth (Bi) doping. We find that the introduction of Bi can increase the initial valance state of Ru in Bi0.15Ru0.85O2, which can promote the activation of Ru active sites, and facilitate the reaction kinetics of acidic OER. Besides, the presence of Bi can strengthen the electron interaction to maintain the structure stability and improve the electrocatalytic performance by reducing the energy barriers and avoiding the overoxidation of active species. The obtained Bi0.15Ru0.85O2catalyst shows a low overpotential of 200.0 mV to reach a current density of 10 mA cm–2under acidic media, and a long-term stability for over 100 hours. Our work provides an important inspiration to rational design RuO2-based electrocatalysts with high activity and durability toward acidic OER.

Exploring bifunctional electrocatalysts with high-efficiency and stability toward overall water splitting is desirable for sustainable energy technologies, yet challenging. Herein, we report the construction of Ni3N on the surface of Ni-MOF-74 through an in-situnitriding process. The obtained Ni-MOF-74/Ni3N exhibits remarkable HER activity with an overpotential of 73 mV to deliver 10 mA cm−2. Theoretical calculations and experimental study demonstrate the electron transport between Ni3N and Ni-MOF-74, leading to the improved H2O adsorption, optimized hydrogen adsorption, and increased Haddiffusion, which contributes to the enhanced HER performance. Besides, the obtained Ni-MOF-74/Ni3N also possesses outstanding activity toward OER and overall water splitting.

Developing RuO2-based electrocatalysts with high activity and stability for acidic oxygen evolution reaction (OER) is highly desirable but remains a challenge. More critically, strategies for rational manipulation of the reaction pathway of RuO2from a kinetically favorable but unstable lattice oxygen oxidation mechanism (LOM) pathway to an adsorption evolution mechanism (AEM) pathway are still elusive. Herein, we report the synthesis of Ce-doped RuO2catalysts with the existence of oxygen vacancies (Ce-RuO2-x). Experimental results and density functional theory (DFT) calculations reveal that Ru valence state is lowered with the formation of Ce-O-Ru local structure, and Ru-O covalency is decreased, which suppress the surface Ru demetallation and lattice oxygen loss, resulting in greatly enhanced durability toward acidic OER. Moreover, the synergistic effect between Ce-O-Ru local structure and oxygen vacancies can be conducive to the stabilization of OOH∗, leading to a manipulated reaction pathway from LOM to AEM and reduced energy barrier of the rate-determining step.

Inorganic porous materials are prevailing in energy storage, environment remediation, and catalysis; however, it is attractive to control the spatial arrangement of heterometals in these materials with atomic accuracy. Here, we report the precise positioning of metals with identical valence, coordination number, and similar size, such as Zn (II) and Co (II), to generate an alternating sequence in a multivariate (MTV) metal-organic framework (MOF), ZnCo-MTV-MOF-699, with a rare sheet secondary building unit. This is achieved by precoding their coordination number in a parent MOF, ZnCo-MOF-69C, followed by single-crystal-to-single-crystal transformation, where the entire process is monitored in situby time-resolved small-angle X-ray scattering. Coordination number precoding of other metal pairs, Zn-Ni and Zn-Cu, in MTV-MOFs is also obtained. The sequence-coded MTV-MOF exhibits a much lower overpotential than that of the non-coded counterpart in oxygen evolution reaction, unveiling the power of metal sequence control.

Post-synthetic functionalization of terminal ligand in NiFe-MOF nanosheet through nitridation has been firstly developed. The irreversible phase reconstruction from amino ligand oxidation lead to the enhanced OER performance.

We report the use of metal–organic frameworks (MOFs) for the selective separation of nucleic acids (DNA and RNA) with different secondary structures through size, shape, length, and capability of conformational transition. Three MOFs with precisely controlled pore environments, Co-IRMOF-74-II, -III, and -IV, composed of Co2+and organic linkers (II, III, and IV), respectively, were used for the inclusion of nucleic acid into their pores from the solution. This was proven to be a spontaneous process from disordered free state to restricted ordered state via circular dichroism (CD) spectroscopy. Three critical factors were identified for their inclusion: (1) size selection induced by steric hindrance, (2) conformation transition energy selection induced by stability, and (3) molecular weight selection. These selection rules were used to extract nucleic acids with flexible and unstable secondary structures from complex mixtures of multiple nucleic acids, leaving those with rigid and stable secondary structures in the mother liquor. This provides the possibility to separate and enrich nucleic acids in bulk through their different structure feature, which is highly desirable in genome-wide structural measurement of nucleic acids. Unlike methods that rely on specific binding antibodies or ligand, this MOF method is capable of selecting all kinds of nucleic acids with similar secondary structure features; therefore, it is suitable for the handling of a large variety and quantity of nucleic acids at the same time. This method also has the potential to gather information about the folding stability of biomolecules with secondary structures.