Grain boundary enriched CuO nanobundle for efficient non-invasive glucose sensors/fuel cells

Biomass-derived carbon-sulfur hybrids boosting electrochemical kinetics to achieve high potassium storage performance

Potassium-ion batteries (PIBs) as an emerging battery technology have garnered significant research interest. However, the development of high-performance PIBs critically hinges on reliable anode materials with comprehensive electrochemical performance and low cost. Herein, low-cost N-doped biomass-derived carbon-sulfur hybrids (NBCSHs) were prepared through a simple co-carbonization of the mixture of a biomass precursor (coffee grounds) and sulfur powder. The sulfur in NBCSHs predominantly exists in the form of single-atomic sulfur bonded with carbon atoms (CSC), functioning as main active redox sites to achieve high reversible capacity. Electrochemical evaluations reveal that the NBCSH 1-3 with moderate sulfur content shows significantly improved potassium storage performance, such as a high reversible capacity of 484.7 mAh g-1 and rate performance of 119.4 mAh g-1 at 5 A g-1, 4.5 and 14.7 times higher than that of S-free biomass-derived carbon, respectively. Furthermore, NBCSH 1-3 exhibits stable cyclability (no obvious capacity fading even after 1000 cycles at 0.5 A g-1) and excellent electrochemical kinetics (low overpotentials and apparent diffusion coefficients). The improved performance of NBCSHs is primarily attributed to pseudocapacitance-dominated behavior with fast charge transfer capability. Density functional theory calculations also reveal that co-doping with S, N favors for achieving a stronger potassium adsorbing capability. Assemble K-ion capacitors with NBCS 1-3 as anodes demonstrate stable cyclability and commendable rate performance. Our research envisions the potential of NBCSHs as efficient and sustainable materials for advanced potassium-ion energy storage systems.

Seamless integration of a nickel-based metal-organic framework with three-dimensional substrates for nonenzymatic glucose sensing

The effective integration of nanomaterials with underlying current collectors is a key factor affecting the performance of nonenzymatic glucose sensors, where an inappropriate integration structure often leads to poor electron transport and instability. In this work, a seamless integrated electrode was constructed by the in situ immobilizing of a nickel-based metal-organic framework (Ni-MOF) on a three-dimensional (3D) conductive nickel foam (NF) for highly sensitive and durable glucose sensing. Facilitated by a rapid microwave-assisted reaction, a robust interfacial interaction between the Ni-MOF and the substrate was established through in situ conversion from nickel oxide (NiO). The fabricated Ni-MOF/NF electrode exhibits an excellent limit of detection (LOD) of 2.65 μM and an impressive sensitivity (14.31 mA cm-2 mM-1) within the linear range (4-576 μM), which is significantly boosted compared with that of an electrode prepared by a typical drop-casting method (3.56 mA cm-2 mM-1 in 4-1836 μM). Characterization and electrochemical tests reveal that this integrated structure on the one hand contributes to fast electron transport and thus has enhanced sensitivity and on the other hand leads to exceptional durability with its structural integrity maintained under bending, shaking, and ultrasonication. Moreover, this seamless integration method was also employed to immobilize the Ni-MOF converted from the pre-chemically deposited NiO layer on another type of substrate, 3D carbon paper (CP), demonstrating the versatility of this facile strategy in creating diverse electrochemical electrodes for applications beyond glucose sensing.