Single atom catalysts have been recognized as potential catalysts to fabricate electrochemical biosensors, due to their unexpected catalytic selectivity and activity. Here, we designed and fabricated an ultrasensitive dopamine (DA) sensor based on the flower-like MoS₂ embellished with single Ni site catalyst (Ni-MoS₂). The limit of detection could achieve 1 pM in phosphate buffer solution (PBS, pH = 7.4), 1 pM in bovine serum (pH = 7.4), and 100 pM in artificial urine (pH = 6.8). The excellent sensing performance was attributed to the Ni single atom axial anchoring on the Mo atom in the MoS₂ basal plane with the Ni-S₃ structure. Both the experiment and density functional theory (DFT) results certify that this structural feature is more favorable for the adsorption and electron transfer of DA on Ni atoms. The high proportion of Ni active sites on MoS₂ basal plane effectively enhanced the intrinsic electronic conductivity and electrochemical activity toward DA. The successful establishment of this sensor gives a new guide to expand the field of single atom catalyst in the application of biosensors.

Why many luminescent liquid crystalline polymers (LLCPs) containing aggregation-induced emission luminogen (AIEgen) show weak emission is a question still to be answered. Herein, a series of LLCPs (α-Pns, n = 4, 8, and 12) with polynorbornene as main chain and two α-dicyanodistyrylbenzene (α-DCS) as side chain are successfully synthesized to solve this issue. Differential scanning calorimetry (DSC), polarized light microscopy (PLM), one-dimentional (1D), two-dimentional (2D) middle-angle and wide-angle X-ray scattering (MAXS and WAXS) results demonstrate that the polymers form smectic A (SmA) phase with the side chains interdigitated packed within the smectic layers. Meanwhile, the photophysical properties of α-Pns were investigated by ultraviolet–visible (UV–vis) absorption, steady state and time-resolved spectroscopy, and photothermal effect. Results show that the polymers are AIE active, but emit weak emission. The emission peak of α-Pns film red-shift from 473 to 531 nm, the quantum yield gradually increases from around 1.6% to 14.7%, and the photothermal conversion efficiency decreases from 39% to 19% with the alkyl tail length increased. The photothermal effect, but not photoluminescence, dominates the excited state relaxation.

The rational fabrication of highly efficient electrocatalysts with low cost toward oxygen evolution reaction (OER) is greatly desired but remains a formidable challenge. In this work, we present a facile and straightforward method of incorporating NiCo-layered double hydroxide (NiCo-LDH) into GO-dispersed CNTs (GO-CNTs) with interconnected configuration. X-ray absorption spectroscopy (XAS) reveals the strong electron interaction between NiCo-LDH and the underlying GO-CNTs substrate, which is supposed to facilitate charge transfer and accelerate the kinetics for OER. By tuning the amount of CNTs, the optimized NiCo-LDH/GO-CNTs composite can achieve a low overpotential of 290 mV at 10 mA·cm⁻² current density, a small Tafel slope of 66.8 mV·dec⁻¹ and robust stability, superior to the pure NiCo-LDH and commercial RuO₂ in alkaline media. The preeminent oxygen evolution performance is attributed to the synergistic effect stemming from the merits and the intimate electron interaction between LDH and GO-CNTs. This allows NiCo-LDH/GO-CNTs to be potentially applied in an industrial non-noble metal-based water electrolyzer as the anodic catalysts.

L1₀-FePt nanoparticles (NPs) with high chemical ordering represent effective electrocatalysts to reduce the cost and enhance their catalytic performance in fuel cells. A molecular strategy of preparing highly ordered FePt NPs was used by direct pyrolysis of a Fe, Pt-containing bimetallic complex. The resultant L1₀-FePt NPs had very high crystallinity as reflected by the obvious diffraction patterns, clear lattice fringes and characteristic X-ray diffraction peaks, etc. Besides, the strong ferromagnetism with room temperature coercivity of 27 kOe further confirmed the face-centered tetragonal (fct) phase in good agreement with the ordered nanostructures. The FePt NPs can be used as electrocatalysts to catalyze oxygen reduction reaction (ORR) in an O₂-saturated 0.1 M HClO₄ solution and hydrogen evolution reaction (HER) in the 0.5 M H₂SO₄ electrolyte with much better performance than commercial Pt/C, and showed quite high stability after 10, 000 cycles. The strategy utilizing organometallic precursors to prepare metal alloy NPs was demonstrated to be a reliable approach for improving the catalytic efficiency in fuel cells.