Seaweed-like phosphates/MOF heterostructures as a synergistic electrocatalyst for alcohol oxidation.

A series of seaweed-like heterogeneous Co3(PO4)2/Ni3(PO4)2/MOF-74-x electrocatalysts were synthesized via a hydrothermal method. The optimal composite exhibits excellent catalytic performance toward methanol/ethanol oxidation reactions (MOR/EOR) with peak current densities reaching 27.5 and 32.6 mA cm-2, respectively. This work heralds the advent of more efficient heterogeneous electrocatalysts for DAFCs and other energy conversion systems.

Recent Advances and Perspectives on the Promising High-Voltage Cathode Material of Na3 (VO)2 (PO4 )2 F.

Na3 (VO)2 (PO4 )2 F (NVOPF) has emerged as one of the most promising cathode materials for sodium-ion batteries (SIBs) attributed to its high specific capacity (130 mAh g-1 ), high operation voltage (>3.9 V vs Na+ /Na), and excellent structural stability (<2% volume change). However, the comparatively low intrinsic electronic conductivity (≈10-7 S cm-1 ) of NVOPF leads to unsatisfactory electrochemical performance, especially at high rates, limiting its practical applications. To improve the conductivity and enhance Na storage performance, many efforts have been devoted to designing NVOPF, including morphology optimization, hybridization with conductive materials, metal-ion doping, Na-site regulation, and F/O ratio adjustment. These attempts have shown some encouraging achievements and shed light on the practical application of NVOPF cathodes. This work aims to provide a general introduction, synthetic methods, and rational design of NVOPF to give a deeper understanding of the recent progress. Additionally, the unique microstructure of NVOPF and its relationship with Na storage properties are also described in detail. The current status, as well as the advances and limitations of such SIB cathode material, are reported. Finally, future perspectives and guidance for advancing high-performance NVOPF cathodes toward practical applications are presented.

Nonenzymatic Electrochemical Sensing Platform Based on 2D Isomorphic Co/Ni-Metal-Organic Frameworks for Glucose Detection.

Two-dimensional metal-organic framework (MOF) crystalline materials possess promising potential in the electrochemical sensing process owing to their tunable structures, high specific surface area, and abundant metal active sites; however, developing MOF-based nonenzymatic glucose (Glu) sensors which combine electrochemical activity and environmental stability remains a challenge. Herein, utilizing the tripodic nitrogen-bridged 1,3,5-tris(1-imidazolyl) benzene (TIB) linker, Co2+ and Ni2+, two 2D isomorphic crystalline materials, including Co/Ni-MOF {[Co (TIB)]·2BF4} (CTGU-31) and {[Ni(TIB)]·2NO3} (CTGU-32), with a binodal (3, 6)-connected kgd topological net were firstly synthesized and fabricated with conducting acetylene black (AB). When modified on a glassy carbon electrode, the optimized AB/CTGU-32 (1:1) electrocatalyst demonstrated a higher sensitivity of 2.198 µA µM-1 cm-2, a wider linear range from 10 to 4000 µM, and a lower detection limit (LOD) value (0.09 µM, S/N = 3) compared to previously MOF-based Glu sensors. Moreover, AB/CTGU-32 (1:1) exhibited desirable stability for at least 2000 s during the electrochemical process. The work indicates that MOF-based electrocatalysts are a promising candidate for monitoring Glu and demonstrate their potential for preliminary screening for diabetes.

Ar plasma assists in enhanced oxygen evolution kinetics of MOG-derived multicomponent transition metal sulfides.

Transition metal sulfides are low-cost oxygen evolution reaction (OER) electrocatalysts that can potentially substitute noble metal catalysts. However, the adsorption process of their OER is impeded by their intrinsic poor catalytic activity. Constructing heterojunction and vacancy defects in transition metal sulfides is an efficient method to promote the process of oxygen evolution. Herein, a facile approach based on in situ sulfurization of metal-organic gels (MOGs) and a short-time plasma treatment was developed to fabricate vacancy-modified polymetallic sulfides heterojunction. The synergistic effect of the multi-component heterojunction and sulfur vacancy contributed greatly to improving the electron migration efficiency and OER ability of the electrocatalyst. As a result, the optimum oxygen evolution activity was achieved with appropriate surface vacancy concentrations by regulating the plasma radio frequency powers. The plasma-treated catalyst under 400 W showed the best OER performance (lower overpotential of 235 mV in 1 M KOH solution with the Tafel slope of 31 mV dec-1) and good durability over 11 h of chronopotentiometry testing. This work sheds new light on constructing multimetal-based heterojunction electrocatalysts with rich vacancy defects for oxygen evolution reactions.

Thermal treatment for promoting interfacial interaction in Co-BDC/Ti3C2Tx hybrid nanosheets for hybrid supercapacitors.

The design and synthesis of high-performance metal-organic frameworks (MOFs)-based electrodes are important for hybrid supercapacitors (HSC). Herein, enhanced interfacial interaction in Co-BDC/Ti3C2Tx (denoted as CoTC) hybrid nanosheets is achieved through thermal treatment, giving remarkably improved capacity performance compared with CoTC. The low temperature annealing treatment enables modulation of the bridging bonds content of CoTC and thus regulates the interfacial coupling effect between Co-BDC and Ti3C2Tx. Moreover, both the detailed XPS and XANES analysis reveal that the strong interfacial interactions between the two components promote a partial electron transfer from Ti3C2Tx to Co-BDC through the Ti-O-Co interfacial bonds. Consequently, it endows the Co-BDC with enhanced conductivity as well as the higher valence of Ti species in Ti3C2Tx, hence contributes a remarkable enhanced specific capacity. This work will provide a pathway to design advanced MOF/MXene materials for HSC.