Nonmodified Laser-Induced Graphene Sensors for Lead-Ion Detection

Abstract

Electrochemical detection, especially anodic stripping voltammetry (ASV), has been widely used in the detection of heavy metal ions because of its high sensitivity, low detection limit, as well as on-site and real-time detection capability. However, ASV detection typically relies on modified sensors, which complicates the preparation process and introduces contaminants to the tested solutions. Herein, we developed a preconcentration relaxation strategy to improve detection performances of bare sensors without modification. Specifically, in the preconcentration step of ASV, the solution stirring did not run throughout the whole preconcentration process but stopped before the end of preconcentration, remaining as a relaxation period for metal ions fully depositing. To verify this strategy, we fabricated porous laser-induced graphene sensors without modification to detect lead ions. With the preconcentration strategy, the detection linear range was widened from 30−100 to 1−100 μg•L −1 , and the sensitivity was increased from 0.1362 μA•(μg•L −1 ) −1 to 0.1772 μA•(μg•L −1 ) −1 in 1−5 μg•L −1 and 0.7081 μA•(μg•L −1 ) −1 in 10−100 μg•L −1 . Moreover, the limit of detection reached 0.5 μg•L −1 (S/N = 3). This work sheds light on the accurate and effective detection of heavy metal ions.

Photocatalytic Coupling of CH4 and CO2 to Ethanol on Asymmetric Ce−O−Zn Sites

“…High‐resolution transmission electron microscopy (HRTEM) images of the all the X%‐Ce─ZnO samples displayed distinct lattice spacings of 0.248 and 0.311 nm (Figure 2c; Figure S2, Supporting Information), corresponding to the ZnO(101) and the CeO 2 (111) planes, respectively. [ 22,23 ] For comparison, the single metal oxide CeO 2 or ZnO catalysts retained the morphologies and sizes of their respective components in the composite catalysts (Figure S3, Supporting Information). For the 10%‐Ce─ZnO sample, abundant defects were observed on the edges of those two oxides (Figure 2c; Figure S4, Supporting Information), suggesting the existence of rich Ce─O─Zn structures.…”

Modulation of Phase Transition in Cobalt Selenide with Simultaneous Construction of Heterojunctions for Highly‐Efficient Oxygen Electrocatalysis in Zinc–Air Battery

“…[ 67 ] In the Co 2p XPS spectra, the ratio of Co 3+ /Co 2+ (≈3.8) after the OER test is higher than that of pristine catalyst (≈1.19) (Figure S23, Supporting Information), indicating that partial Co 2+ is oxidized into Co 3+ to form the CoOOH on the c‐CoSe 2 ‐CoN/NC during the OER process. [ 68 ] Furthermore, a slight change in the ratio of Co 3+ /Co 2+ (≈1.6) is observed after the ORR stability test, further indicating that c‐CoSe 2 ‐CoN/NC possesses good structural stability. To understand the reaction mechanisms more intuitively, Figure 6h illustrates the origins of electrocatalytic activity and the fate of active ingredients in c‐CoSe 2 ‐CoN/NC after ORR/OER.…”

A High‐Performance Phosphate Potentiometric Sensor Based on Cobalt Nanoparticles Electroplated on Hierarchically Porous Laser‐Induced Graphene

“…[39,40] The conductivity is another factor determining the detection performance of electrochemical sensors, i.e., higher conductivity is associated with higher detection performance. [31,32] In order to improve the conductivity of LIG, we changed laser power and laser speed and took the sheet resistance as the indicator. It was found that as the laser power increases from 9.2 to 9.6 W, the sheet resistance of LIG decreases first and then increases (Figure 2e).…”

“…As shown in Figure 2f, the charge transfer resistance (R ct ) of LIG can be read as 3.5 Ω from the diameter of the minicircle, indicating the low electrochemical impedance and strong charge transfer ability of LIG. [32,43]…”