Electrosynthesis of HO through a two-electron oxygen reduction reaction by carbon based catalysts: From mechanism, catalyst design to electrode fabrication.

Hydrogen peroxide (HO) is an efficient oxidant with multiple uses ranging from chemical synthesis to wastewater treatment. The in-situ HO production via a two-electron oxygen reduction reaction (ORR) will bring HO beyond its current applications. The development of carbon materials offers the hope for obtaining inexpensive and high-performance alternatives to substitute noble-metal catalysts in order to provide a full and comprehensive picture of the current state of the art treatments and inspire new research in this area.

Engineering the Local Atomic Environments of Indium Single-Atom Catalysts for Efficient Electrochemical Production of Hydrogen Peroxide.

The in-depth understanding of local atomic environment-property relationships of p-block metal single-atom catalysts toward the 2 e oxygen reduction reaction (ORR) has rarely been reported. Here, guided by first-principles calculations, we develop a heteroatom-modified In-based metal-organic framework-assisted approach to accurately synthesize an optimal catalyst, in which single In atoms are anchored by combined N,S-dual first coordination and B second coordination supported by the hollow carbon rods (In SAs/NSBC). The In SAs/NSBC catalyst exhibits a high H O selectivity of above 95 % in a wide range of pH.

Amplifying anti-flooding electrode to fabricate modular electro-fenton system for degradation of antiviral drug lamivudine in wastewater.

The advanced oxidation based on in-situ hydrogen peroxide production using carbon air cathode is very potential for wastewater treatment. However, catalyst flooding and complex assembly patterns are the bottleneck limiting the air cathode to the long-term and large-scale application. In this work, a novel anti-flooding air-breathing cathode (ABC) was prepared by a simple rolling-spraying method with relatively low price commercial materials.

Graphene family for hydrogen peroxide production in electrochemical system.

The development of carbon-based materials to catalyze two-electron (2e) pathway of oxygen reduction reaction (ORR) offers great potential for hydrogen peroxide (HO) production. As a class of novel two-dimensional (2D) carbon materials, graphene and its derivatives have raised increasing attention as excellent noble-metal-free catalysts in 2e ORR due to their unique structure, physical and chemical properties. This review focuses on the synthesis of main graphene family members and graphene based electrodes, as well as their applications for HO generation in electrochemical systems.

Excessive extracellular polymeric substances induced by organic shocks accelerate electron transfer of oxygen reducing biocathode.

Electrotrophic bacteria on cathodes are promising substitutes to precious metals as oxygen reduction reaction catalysts in bioelectrochemical systems (BESs). Leading the anodic effluent to the biocathode has additional benefits of neutralizing pH and removing residual pollutants. However, the overflow of excessive organic pollutants inhibits the activity of autotrophic biocathodes.

Graphite accelerate dissimilatory iron reduction and vivianite crystal enlargement.

Biomineralized vivianite induced by dissimilatory iron reduction bacteria (DIRB) has received increasing attention because it alleviates phosphorus crisis and phosphorus pollution simultaneously. However, the relatively small crystal size and low Fe(III) reduction rate restrict the separation and recovery of vivianite. In this study, graphite was selected as additive to enhance vivianite biomineralization with soluble ferric citrate and insoluble hematite as two representative electron acceptors.

Fenton-based technologies as efficient advanced oxidation processes for microcystin-LR degradation.

In recent years, the safety and ecology threat of cyanobacterial burst has drawn wide concern, especially the release of toxic microcystin-LR (MC-LR). To break through the bottleneck of uncomplete MC-LR degradation by conventional physical-chemistry methods, Fenton-based advanced oxidation processes (AOPs) developed rapidly due to striking degradation efficiency through the potent hydroxyl radicals (HO·) oxidation. Herein, a comprehensive overview is presented on the recent achievements of the various Fenton-based technologies (including conventional Fenton, photo-Fenton, electro-Fenton, ozone-Fenton and sono-Fenton) for MC-LR degradation.

A highly sensitive bioelectrochemical toxicity sensor and its evaluation using immediate current attenuation.

Electroactive biofilm (EAB) sensor had shown great potential in the field of early warning of toxicants in water because of the low-cost and broad-spectrum. However, the traditional calculation of sensitivity strongly relied on the time and concentration gradient which weakened time-efficiency of the sensor. Moreover, the sensitivity could be further improved to respond trace concentrations.

Autogenically Secretes Fulvic Acid to Facilitate the Dissimilated Iron Reduction and Vivianite Recovery.

Biosynthetic organic matters, such as humus, play important roles in iron and phosphorus cycling in soil and aquatic systems. As an important member of humus, fulvic acid (FA) is ubiquitous in different environmental media, such as water, soil, and sediments. In this study, we fabricated the network among phosphate supply, metabolism pathway of FA, iron reduction, and vivianite recovery at the batch scale.

Revealing Decay Mechanisms of HO-Based Electrochemical Advanced Oxidation Processes after Long-Term Operation for Phenol Degradation.

Hydrogen peroxide (HO)-based electrochemical advanced oxidation processes (EAOPs) have been widely attempted for various wastewater treatments. So far, stability tests of EAOPs are rarely addressed and the decay mechanism is still unclear. Here, three HO-based EAOP systems (electro-Fenton, photoelectro-Fenton, and photo+ electro-generated HO) were built for phenol degradation.

Acetate limitation selects Geobacter from mixed inoculum and reduces polysaccharide in electroactive biofilm.

Bioelectrochemical systems (BESs) are widely investigated as a promising technology to recover bioenergy or synthesize value-added products from wastewaters. The performance of BES depends on the activity of electroactive biofilm (EAB). As the core of BES, it is still unclear how the EAB is formed from mixed inoculum, and how exoelectrogens compete with non-exoelectrogens.

Unignorable toxicity of formaldehyde on electroactive bacteria in bioelectrochemical systems.

Formaldehyde poses significant threats to the ecosystem and is widely used as a toxicity indicator to obtain electrical signal feedback in electroactive biofilm (EAB)-based sensors. Although many optimizations have been adopted to improve the performance of EAB to formaldehyde, nearly no studies have discussed the toxicity of formaldehyde to EAB. Here, EABs were acclimated with a stable current density (8.

Superhydrophobic Air-Breathing Cathode for Efficient Hydrogen Peroxide Generation through Two-Electron Pathway Oxygen Reduction Reaction.

Electrochemical catalysis of carbon-based material via two-electron pathway oxygen reduction reaction (ORR) offers great potential for in situ hydrogen peroxide (HO) production. In this work, we tuned catalyst mesostructure and hydrophilicity/hydrophobicity by adjusting polytetrafluoroethylene (PTFE) content in graphite/carbon black/PTFE hybrid catalyst layer (CL), aimed to improving the two-electron ORR activity for efficient HO generation. As the only superhydrophobic CL with initiating contact angles of 141.

Highly efficient electro-generation of HO by adjusting liquid-gas-solid three phase interfaces of porous carbonaceous cathode during oxygen reduction reaction.

Equilibrium of three reactants (oxygen, proton and electron) in oxygen reduction reaction at large current flux is necessary for highly efficient electro-generation of HO. In this work, we investigated reactants equilibrium and HO electrochemical production in liquid-gas-solid three phase interfaces on rolling cathodes with high electroactive area. Electrocatalytic reaction accelerated the electrolyte intrusion into hydrophobic porous catalyst layer for higher electroactive surface area, resulting in a 21% increase of HO yield at 15 mA cm.

Heterotopic formaldehyde biodegradation through UV/H O system with biosynthetic H O.

Biodegradation was regarded an environmentally benign and cost-effective technology for formaldehyde (CH O) removal. However, the biotoxicity of CH O inhibited microbial activity and decreased removal performance. We developed a novel heterotopic CH O biodegradation process that combined bioelectrochemical system (BES) and UV/H O .

Optimal set of electrode potential enhances the toxicity response of biocathode to formaldehyde.

The autotrophic biocathode was promising as a broad spectrum, rapid-responding and sensitive sensing element for the early warning of toxicants in water. However, we found that the baseline current and the responsivity strongly relied on the cathode potential. Here we poised cathode potentials at 0, -0.

A novel electro-coagulation-Fenton for energy efficient cyanobacteria and cyanotoxins removal without chemical addition.

Harmful cyanobacterial bloom is a serious threat to global aquatic ecology and drinking water safety. Electro-Fenton (EF) has emerged as an efficient process for cyanobacteria and cyanotoxins removal, but high consumption of energy and chemicals remain a major bottleneck. This study presents a novel convertible three-electrodes Electro-Coagulation-Fenton process for cyanobacteria and cyanotoxins removal with low energy consumption and no chemicals addition.

Phosphorus Competition in Bioinduced Vivianite Recovery from Wastewater.

Phosphorus undergoes a one-way flow from minerals to soil to water, which creates a phosphorus crisis as well as aquatic eutrophication. Dissimilatory metal reduction bacterial (DMRB)-induced vivianite recovery from wastewater is a promising route to solve these problems synthetically. In this study, phosphorus competition between biomass growth and bioinduced vivianite mineralization was investigated at the batch scale.

Repeated transfer enriches highly active electrotrophic microbial consortia on biocathodes in microbial fuel cells.

Cathodic oxygen reduction catalyzed by autotrophic bacteria instead of a precious metal is a promising method to make use of microbial fuel cells (MFCs) in wastewater treatment with electricity production. However, the ecology of electrotrophic microbial consortia in wastewater systems that function as the catalyst for cathodic oxygen reduction is complicated and the electron transfer mechanisms are still unknown, which prevents further improvements of the biocathode performance. Enriched by the repeated transfer of a mature electrotrophic microbial consortia to new cathodes over 10 generations in 230 days, the start-up time was shortened from 21.

Swift Acid Rain Sensing by Synergistic Rhizospheric Bioelectrochemical Responses.

Acid rain poses significant threats to crops and causes a decline in food production, but current monitoring and response to acid rain damage is either slow or expensive. The direct damage observation on plants can take several hours to days when the damage is irreversible. This study presents a real time bioelectrochemical monitoring approach that can detect acid rain damage within minutes.

Acid pretreatment of three-dimensional graphite cathodes enhances the hydrogen peroxide synthesis in bioelectrochemical systems.

Graphite is a potential catalyst for hydrogen peroxide (HO) synthesis in bioelectrochemical systems (BESs) because of its high performance and low cost. In this study, acidic pretreatment method was performed on raw graphite powder to optimize the performance of three-dimensional graphite cathode and increase the HO yield. Through this method, the production rate of HO increased by 46.

Subminimal inhibitory concentration (sub-MIC) of antibiotic induces electroactive biofilm formation in bioelectrochemical systems.

Electroactive biofilms (EABs) generated from mixed inocula are attractive due to their unique direct extracellular electron transfer abilities and potential use in water pollution control. In this study, for the first time, we identified a chemical that can be used for EAB regulation (both inhibition and promotion). We confirmed that tobramycin, an antibiotic previously demonstrated to inhibit the activity of EABs, is an agonist of EAB formation at subminimal inhibitory concentrations (sub-MICs).