Urchin-like CO2-responsive magnetic microspheres for highly efficient organic dye removal

CO2-responsive materials have emerged as promising adsorbents for the remediation of refractory organic dyes-contaminated wastewater without the formation of byproducts or causing secondary pollution. However, realizing the simultaneous adsorption-separation or complete removal of both anionic and cationic dyes, as well as achieving deeper insights into their adsorption mechanism, still remains a challenge for most reported CO2-responsive materials. Herein, a novel type of urchin-like CO2-responsive Fe3O4 microspheres (U-Fe3O4 @P) has been successfully fabricated to enable ultrafast, selective, and reversible adsorption of anionic dyes by utilizing CO2 as a triggering gas. Meanwhile, the CO2-responsive U-Fe3O4 @P microspheres exhibit the capability to initiate Fenton degradation of non-adsorbable cationic dyes. Our findings reveal exceptionally rapid adsorption equilibrium, achieved within a mere 5 min, and an outstanding maximum adsorption capacity of 561.2 mg g-1 for anionic dye methyl orange upon CO2 stimulation. Moreover, 99.8% of cationic dye methylene blue can be effectively degraded through the Fenton reaction. Furthermore, the long-term unresolved interaction mechanism of organic dyes with CO2-responsive materials is deciphered through a comprehensive experimental and theoretical study by density functional theory. This work provides a novel paradigm and guidance for designing next-generation eco-friendly CO2-responsive materials for highly efficient purification of complex dye-contaminated wastewater in environmental engineering.

One-pot wet-chemical fabrication of 3D urchin-like core-shell Au@PdCu nanocrystals for electrochemical breast cancer immunoassay

Carbohydrate antigen 15-3 (CA15-3) is an important biomarker for early diagnosis of breast cancer. Herein, a label-free electrochemical immunosensor was built based on three-dimensional (3D) urchin-like core-shell Au@PdCu nanocrystals (labeled Au@PdCu NCs) for highly sensitive detection of CA15-3, where K3[Fe(CN)6] behaved as an electroactive probe. The Au@PdCu NCs were synthesized by a simple one-pot wet-chemical approach and the morphology, structures, and electrocatalytic property were investigated by several techniques. The Au@PdCu NCs prepared worked as electrode material to anchor more antibodies and as signal magnification material by virtue of its exceptional catalytic property. The developed biosensor exhibited a wide linear detection range from 0.1 to 300 U mL-1 and a low limit of detection (0.011 U mL-1, S/N = 3) for determination of CA15-3 under the optimal conditions. The established biosensing platform exhibits some insights for detecting other tumor biomarkers in clinical assays and early diagnosis.

Bismuth sulfide microstructures decorated with functionalized boron nitride composite for electrochemical detection of sulfadiazine

In this work, the hydrothermal method was used to synthesize f-BN@Bi₂S₃ nanocomposite and used as an electrocatalyst for the detection of sulfadiazine (SD) drug. Various spectroscopic and voltammetric techniques were adopted to evaluate the morphological and structural features of the prepared materials. The modification of the electrode results in good electrocatalytic activity and excellent sensitive towards the oxidation of SD because of its huge active surface area, high sensitivity, and electrical conductivity provided by the synergistic effects of the f-BN@Bi₂S₃ nanocomposite. This modified electrode exhibited linearity in the range 0.01-62 µM at E_pa = 0.93 V (vs. Ag/AgCl). Furthermore, according to the electrochemical reaction towards the SD, a modified electrode of f-BN@Bi₂S₃ has a LOD value of 0.0015 µM, sensitivity (8.42 μA·μM^-1·cm^-2), good anti-interfering ability, and good repeatability. The suggested electrochemical sensor has high detection performance for monitoring water and urine samples. Notably, relative standard deviations (RSD) and recoveries of the proposed sensor for spiked water and urine samples are in the ranges of 0.014-0.75% and 98.97-99.98% (n = 3), respectively.

Low-cost urchin-like silicon-based anode with superior conductivity for lithium storage applications

Poor rate and cycling performance are the most critical drawbacks for Si-based anodes on account of their inferior conductivity and colossal volumetric expansion during lithiation/delithiation. Here we report the fabrication of structurally-integrated urchin-like Si anode, which provides prominent structural stability and distinguished electron and ion transmission pathways for lithium storage. The inexpensive solid Si waste from organosilane industry after acid-washed and further ball-milling serves as the pristine Si-source in this work. Carbon nanotubes (CNTs) are in-situ grown outside Si microparticles, resulting in an urchin-like structure (Si/CNTs). The optimized Si/CNTs presents ascendant invertible capacity and rate performance, achieving up to 920 mAh g^-1 beyond 100 cycles at 100 mA g ^-1, and a capacity of 606.2 mAh g^-1 at 1 A g ^-1 after long cycling for 1000 cycles. The proposed scalable synthesis can be adopted to advance the performance of other electrode materials with inferior conductivity and enormous volume expansions during cycling.

Urchin-like non-precious-metal bifunctional oxygen electrocatalysts: Boosting the catalytic activity via the In-situ growth of heteroatom (N, S)-doped carbon nanotube on mesoporous cobalt sulfide/carbon spheres

We successfully design and construct urchin-like non-precious-metal bifunctional oxygen electrocatalysts via a two-step pyrolysis process, where nitrogen, sulfur co-doped carbon nanotube frameworks are grafted onto mesoporous cobalt sulfide/nitrogen, sulfur co-doped carbon spheres. The urchin-like structure grants large electrochemically active area, good electron and mass transfer capability, as well as excellent structural stability. Nitrogen, sulfur co-doped carbon can synergistically enhance the catalytic activity of cobalt sulfide sites, and also contribute to the exposure of heteroatom-induced active sites, such as, pyridinic N, graphitic N, and C-S-C. Hence, benefiting from the unique architecture and efficient catalytic sites, the resulting catalysts demonstrate excellent bifunctional catalytic activities with a positive half-wave potential of 0.860 V vs. RHE for oxygen reduction reaction and low overpotential of ∼390 mV at the current density of 10 mA cm^-2 for oxygen evolution reaction in alkaline medium, which can rank them among one of the most promising cobalt-based bifunctional oxygen electrocatalysts reported previously.