Magnéli-Phase Ti₄O₇-Doped Laser-Induced Graphene Surfaces and Filters for Pollutant Degradation and Microorganism Removal

Abstract

Laser-induced graphene (LIG) has recently become a point of attraction globally as an environmentally friendly method to fabricate graphene foam in a single step using a CO 2 laser. The electrical properties of LIG are studied in different environmental applications, such as bacterial inactivation, antibiofouling, and pollutant sensing. Furthermore, metal or nonmetal doping of graphene enhances its catalytical performance in pollutant degradation and decontamination. Magneĺi phase (Ti n O 2n−1 ) is a substoichiometric titanium oxide known for its high electrocatalytic behavior and chemical inertness and is being explored as a membrane or electrode material for environmental decontamination. Here, we show the fabrication and characterization of LIG−Magneĺi-phase (Ti 4 O 7 ) titanium suboxide composites as electrodes and filters on poly(ether sulfone). Unlike undoped LIG electrodes, the doped Ti 4 O 7 −LIG electrodes exhibit enhanced electrochemical activity, as demonstrated in electrochemical characterization using cyclic voltammetry and electrochemical impedance spectroscopy. Due to the in situ generation of hydroxyl radicals on the surface, the doped electrodes exhibit increase in methylene blue degradation and microorganism removal. Effects of voltage and doping were examined, resulting in a clear trend of degradation and decontamination performance proportional to the doping concentration and applied voltage giving the best result at 2.5 V for 10% Ti 4 O 7 doping. The LIG−Ti 4 O 7 surfaces also showed biofilm inhibition against mixed bacterial culture. The flowthrough filtration using a LIG−Ti 4 O 7 conductive filter showed complete bacterial killing with 6 log removal in the permeate at 2.5 V, an enhancement of ∼2.5 log compared to undoped LIG filters at a flow rate of ∼500 L m −2 h −1 . The facile fabrication of Ti 4 O 7doped LIG with enhanced electrochemical properties can be effectively used for energy and environmental applications.

Electrochemical inactivation of enteric viruses MS2, T4, and Phi6 using doped laser-induced graphene electrodes and filters

“…This can be attributed to the doped electrode's enhanced electrocatalytic and electrochemical activity on the application of voltage, which coincides with previous reports. 37,54 For T4 phage, increasing the doping concentration had no significant effect on the inactivation, as presented in Fig. 2e.…”

“…[32][33][34][35][36] In light of this, doping of titanium dioxide (TiO 2 ) in polyether sulfone (PES) polymers can generate sub-stoichiometric titanium dioxide (TiO x )-doped LIG on laser irradiation, which consists of unique electrical and optical properties. 37,38 However, studies on titanium suboxides such as Magnéli phase-based LIG composites are limited, necessitating their utilization for electrochemical inactivation of viruses.…”

Persulfate enhanced ciprofloxacin removal from water by laser-induced graphene-based electroconductive ultrafiltration membrane

“…17 The LIG method is a simple, reagent-free, solventfree, and single-step process of graphene formation on any carbonaceous substrate via laser scribing. [18][19][20] Due to graphene and its electroconductive nature, LIG filters and composite ECMs have shown good contaminant rejection and antibacterial, antiviral, and antibiofilm properties. [21][22][23][24][25] Detailed literature reviews on ECMs, LIG and their environmental application can be found elsewhere.…”

Three Dimensional Graphene/Copper Dual Networks as Composite Conductors with Enhanced Current Carrying Capacity

“…In 2014, Tour’s prepared a three-dimensional porous graphene (LIG) with excellent conductivity using polyimide (PI) as a carbon source through CO 2 laser direct writing . Subsequently, LIG was widely used as a 3D conductive graphene framework and combined with metals and their oxides via in-suit or post-modification methods, demonstrating immense potential in applications such as strain sensors, , electrodes, , supercapacitors, , etc. Chen et al obtained the synthesis of an in situ Cu nanoparticle-modified LIG-Cu composite material by incorporating copper salts into the PI precursor solution, resulting in a significantly enhanced conductivity of 0.37 × 10 7 S m –1 at low Cu loadings which is approximately 3000 times that of pure LIG.…”