Correction to "Controllable Synthesis of a Porous PEI-Functionalized Co3O4/rGO Nanocomposite as an Electrochemical Sensor for Simultaneous as Well as Individual Detection of Heavy Metal Ions".

[This corrects the article DOI: 10.1021/acsomega.1c05989.].

Controllable Synthesis of a Porous PEI-Functionalized Co3O4/rGO Nanocomposite as an Electrochemical Sensor for Simultaneous as Well as Individual Detection of Heavy Metal Ions.

The present study focuses on the strategy of employing an electrochemical sensor with a porous polyethylenimine (PEI)-functionalized Co3O4/reduced graphene oxide (rGO) nanocomposite (NCP) to detect heavy metal ions (HMIs: Cd2+, Pb2+, Cu2+, and Hg2+). The porous PEI-functionalized Co3O4/rGO NCP (rGO·Co3O4·PEI) was prepared via a hydrothermal method. The synthesized NCP was based on a conducting polymer PEI, rGO, nanoribbons of Co3O4, and highly dispersed Co3O4 nanoparticles (NPs), which have shown excellent performance in the detection of HMIs. The as-prepared PEI-functionalized rGO·Co3O4·PEI NCP-modified electrode was used for the sensing/detection of HMIs by means of both square wave anodic stripping voltammetry (SWV) and differential normal pulse voltammetry (DNPV) methods for the first time. Both methods were employed for the simultaneous detection of HMIs, whereas SWV was employed for the individual analysis as well. The limits of detection (LOD; 3σ method) for Cd2+, Pb2+, Cu2+, and Hg2+ determined using the rGO·Co3O4·PEI NCP-modified electrode were 0.285, 1.132, 1.194, and 1.293 nM for SWV, respectively. Similarly, LODs of Cd2+, Pb2+, Cu2+, and Hg2+ were 1.069, 0.285, 2.398, and 1.115 nM, respectively, by DNPV during simultaneous analysis, whereas they were 0.484, 0.878, 0.462, and 0.477 nM, respectively, by SWV in individual analysis.

Facile Synthesis of Highly Dispersed Co3O4 Nanoparticles on Expanded, Thin Black Phosphorus for a ppb-Level NO x Gas Sensor.

Expanded few-layer black phosphorus nanosheets (FL-BP NSs) were functionalized by branched polyethylenimine (PEI) using a simple noncovalent assembly to form air-stable overlayers (BP-PEI), and a Co3O4@BP-PEI composite was designed and synthesized using a hydrothermal method. The size of the highly dispersed Co3O4 nanoparticles (NPs) on the FL-BP NSs can be controlled. The BP-C5 (190 °C for 5 h) sensor, with 4-6 nm Co3O4 NPs on the FL-BP NSs, exhibited an ultrahigh sensitivity of 8.38 and a fast response of 0.67 s to 100 ppm of NO x at room temperature in air, which is 4 times faster than the response of the FL-BP NS sensor, and the lower detection limit reached 10 ppb. This study points to a promising method for tuning properties of BP-based composites by forming air-stable overlayers and highly dispersed metal oxide NPs for use in high-performance gas sensors.

One-step Synthesis of Ordered Pd@TiO2 Nanofibers Array Film as Outstanding NH3 Gas Sensor at Room Temperature.

The one dimensional (1D) ordered porous Pd@TiO2 nanofibers (NFs) array film have been fabricated via a facile one-step synthesis of the electrospinning approach. The Pd@TiO2 NFs (PTND3) contained Pd (2.0 wt %) and C, N element (16.2 wt %) display high dispersion of Pd nanoparticles (NPs) on TiO2 NFs. Adding Pd meshed with C, N element to TiO2 based NFs might contribute to generation of Lewis acid sites and Brønsted acid sites, which have been recently shown to enhance NH3 adsorption-desorption ability; Pd NPs could increase the quantity of adsorbed O2 on the surface of TiO2 based NFs, and accelerated the O2 molecule-ion conversion rate, enhanced the ability of electron transmission. The response time of PTND3 sensor towards 100 ppm NH3 is only 3 s at room temperature (RT). Meantime, the response and response time of the PTND3 to the NH3 is 1 and 14s even at the concentration of 100 ppb. Therefore, the ordered Pd@TiO2 NFs array NH3 sensor display great potential for practical applications.