Electrochemical dechlorination reaction (EDR) is a promising, environmentally friendly, and economically profitable technology for treating chlorinated organic pollutants. For efficient environmental protection, electrocatalysts with high stability and low cost are of extremely significance to the development of EDR technology. Carbon-based materials have aroused broad interest as electrocatalysts for many electrochemical reactions due to their characteristics including large specific surface area, controllable structure, good conductivity, and chemical stability. For EDR, the carbon-based materials also show many unique superiorities, like strong adsorption capacity to chlorinated organic compounds (COCs), excellent catalytic activity and stability, and environmental compatibility. This review starts with a detailed summary on the mechanisms of electrochemical dechlorination (direct and indirect electron transfer pathway) and factors affecting the effectiveness of EDR. Then the paper comprehensively overviews the current progresses of carbon-based materials for EDR of COCs, following their two major application scenarios, i.e., directly as electrocatalysts and as advanced supports for other catalysts. Moreover, the formation of different active sites in carbon-based electrocatalysts and their EDR activities are analyzed. Finally, the current challenges and perspectives in this field are discussed. This review will provide an in-depth understanding for the design of advanced carbon-based materials and promote the development of EDR technology.

Owing to the high theoretical capacity, metal sulfides have emerged as promising anode materials for potassium-ion batteries (PIBs). However, sluggish kinetics, drastic volume expansion, and polysulfide dissolution during charge/discharge result in unsatisfactory electrochemical performance. Herein, we design a core-shell structure consisting of an active bismuth sulfide core and a highly conductive sulfur-doped carbon shell (Bi₂S₃@SC) as a novel anode material for PIBs. Benefiting from its unique core-shell structure, this Bi₂S₃@SC is endowed with outstanding potassium storage performance with high specific capacity (626 mAhdg^-1 under 50 mAdg^-1) and excellent rate capability (268.9 mAhdg^-1 at 1 Adg^-1). More importantly, a Bi₂S₃@SC//KFe[Fe(CN)₆] full cell is successfully fabricated, which achieves a high reversible capacity of 257 mAhdg^-1 at 50 mAdg^-1 over 50 cycles, holding great potentials in practical applications. Density functional theory (DFT) calculations reveal that potassium ions have a low diffusion barrier of 0.54 eV in Bi₂S₃ due to the weak van der Waals interactions between layers. This work heralds a promising strategy in the structural design of high-performance anode materials for PIBs.

A series of carbon nanoparticles (CNPs) with emission wavelength ranging from 483 to 525 nm were prepared by hydrothermal treatment of poly-3-thiopheneacetic acid (PTA) and NaOH. The emission wavelength and surface oxidation degree of CNPs were shown to be controllable by simply adjusting NaOH concentration. These CNPs presented obvious fluorescence spectral response toward copper ions (Cu²⁺) through static quenching caused synergistically by electron transfer and inner filter effect. The O- and S-containing groups on the surface of CNPs were demonstrated to be responsible for their outstanding sensing performance. Based on that, a CNPs-based ratiometric fluorescent probe for Cu²⁺ with a high fluorescence quenching rate constant of 1.4 × 10⁵ L/mol and a short response time (10 s) was developed. Their practical applications in detecting Cu²⁺ in pond water and living cells were also demonstrated.

C dots (CDs) have shown great potential in bioimaging and phototherapy. However, it is challenging to manipulate their fluorescent properties and therapeutic efficacy to satisfy the requirements for clinic applications. In this study, we prepared S, Se-codoped CDs via a hydrothermal method and demonstrated that the doping resulted in excitation wavelength-independent near-infrared (NIR) emissions of the CDs, with peaks at 731 and 820 nm. Significantly, the CDs exhibited a photothermal conversion efficiency of ~58.2%, which is the highest reported value for C nanostructures and is comparable to that of Au nanostructures. Moreover, the CDs had a large two-photon absorption cross section (~30, 045 GM), which allowed NIR emissions and the photothermal conversion of the CDs through the two-photon excitation (TPE) mechanism. In vitro and in vivo tests suggested that CDs can function as new multifunctional phototheranostic agents for the TPE fluorescence imaging and photothermal therapy of cancer cells.

Metal-free, organic-dye-based fluorescent nanorods were fabricated through a simple solvent-exchange procedure. The as-prepared nanorods exhibit low toxicity to living cells and excellent photostability. Furthermore, they are stable in solutions of various pHs and high ionic strength and in solutions with interfering metal ions. Compared with the free DPP-Br molecules in THF, these nanorods exhibit larger Stokes shift, broader absorption spectra, and greatly improved photostability. We successfully demonstrated the application of the nanorods, including their aforementioned beneficial characteristics, as a good fluorescence probe for bio-imaging.