Zhensen Liang,Ye Ma,Xiaoming Wang,Yichang He,Yiquan Liao,Bin Zhang,Minggang Zhao,Hongzhi Cui
Copper ions (Cu 2+ ) pollution poses a serious threat to Marine ecology and fisheries, but the online detection is difficult due to seawater interference. Herein, photo-assisted barrier effect is introduced into electrochemical detection as a driver to generate electrochemical response. The n–n junction barrier exhibits excellent adjusting effect on electrochemical response under photoexcitation and could effectively drive electrochemical response by Cu 2+ adsorption. The prepared Ti/TiO 2 /In 2 O 3 /Chitosan wire is used for direct Cu 2+ detection, and the trace detection with the low detection limit (59.08 n m ) is achieved. The strong interference of seawater is resisted effectively by using photo-assisted barrier effect, and the good recovery rate (94.9–107.1%) in the actual seawater detection make it promising for practical applications. It is a new approach to develop electrochemical sensors by using photo-assisted barrier effect to resist interference.
Tin disulfide (SnS 2 ) nanoplates demonstrate remarkable potential in NO 2 detection due to their unique physical affinity to NO 2 . However, SnS 2 nanoplate-based sensors suffer from high operating temperatures, inadequate sensitivity, and slow recovery due to intrinsic low conductivity and self-stacking issues. To address these challenges, we fabricated vanadium tetrasulfide/SnS 2 (VS 4 /SnS 2 ) composites via a facile hydrothermal method. Results reveal that the addition of VS 4 significantly reduces the resistance of SnS 2 -based sensor. The sensitivity (1.64 ppm −1 ) of the optimized VS 4 /SnS 2 (1:1) sensor to 1 −5 ppm NO 2 is 546.67 times higher than that of the pristine VS 4 sensor. The sensor exhibits ultrafast complete recovery (2.25 s) and a low limit of detection (90 ppb) at 25 ℃. In addition, the VS 4 /SnS 2 (1:1) sensor displays reliable repeatability, outstanding selectivity and long-term stability. These breakthroughs originate from the formation of n-n junctions and a unique three-dimensional hierarchical structure. This work demonstrates a scalable approach for developing highly sensitive and rapid SnS 2 -based NO 2 sensors operating at room temperature.
Metal organic frameworks (MOFs), crystalline solids consisting of organic ligands and metal ions, have attracted increasing interest in various areas, including catalysis and biology. Functionalizable pore interiors and ultrahigh surface-to-volume ratios of MOFs make them excellent materials, especially for surface-enhanced Raman scattering (SERS) by the photoinduced charge transfer (PICT) between the MOFs and adsorbed molecules for SERS signal amplification. In our previous work, we demonstrated a p–n junction-assisted MOF substrate for enhancing the SERS signal through additional charge transfer, while the notable structural characteristics of MOFs benefit the SERS selectivity. However, due to this characteristic, a single MOF can only detect analytes at specific energy levels, thereby reducing the efficiency and limiting the detection range of SERS. To address this challenge, in this article, we attempted to synthesize multiple MOFs on the same substrate to achieve SERS with multiple detection functionality. In this study, we demonstrated a ZIF-8/Zn(OH)2 n–n junction SERS substrate, which can achieve a 4.44 nM limit of detection using methyl orange (MO) as a model analyte, by trapping the additional electrons from Zn(OH)2 to ZIF-8 to provide stronger electromagnetic enhancement. Then, we developed a multiple MOFs-based SERS analytical platform, incorporating both in situ ZIF-8 and ZIF-67, and utilized them together as SERS substrates. These two systems operated independently under different incident light wavelengths and successfully detected MO and Rhodamine 6G, respectively. Furthermore, this approach broadens the detection range of analytes while maintaining the tailorability and selectivity of MOF substrates simultaneously. This work offers a cutting-edge method for creating high-performance SERS substrates by demonstrating the ability to manipulate hot electrons for remarkable Raman amplification.
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