Modified electrolytic manganese dioxide (MEMD) for oxygen generation in alkaline medium

MnOx Film-Coated NiFe-LDH Nanosheets on Ni Foam as Selective Oxygen Evolution Electrocatalysts for Alkaline Seawater Oxidation

Compared to freshwater electrolysis, seawater electrolysis to produce hydrogen is preferable and more promising, but this technology is plagued by the electrode's corrosion and oxidative reactions of the competitive Cl^- ion on the anode. To develop efficient oxygen evolution reaction (OER) catalysts for seawater electrolysis, the ultrathin MnO_x film-covered NiFe-layered double-hydroxide nanosheet array is directly assembled on Ni foam (MnO_x/NiFe-LDH/NF) by hydrothermal and electrodeposition in turn. This catalyst demonstrates excellent OER-selective activity in alkaline saline electrolytes. In 1 M KOH/0.5 M NaCl and 1 M KOH/seawater electrolytes, MnO_x/NiFe-LDH/NF exhibits lower overpotentials at 100 mA cm^-2 (η₁₀₀ values of 265 and 276 mV, respectively) and Tafel slopes (73 and 77 mV decade^-1, respectively) than does the NiFe-LDH/NF electrode (η₁₀₀ values of 298 and 327 mV and Tafel slopes of 91 and 140 mV decade^-1, respectively). In alkaline saline solutions, the stability and durability of the former are also better than those of the latter. The good OER selectivity and catalytic performance are attributed to the MnO_x overlayer that selectively blocks Cl^- anions from approaching catalytic centers, and the good conductivity, fast kinetics, more oxygen vacancies, and abundant active sites of MnO_x/NiFe-LDH/NF. The robust stability is due to the enhanced resistance for Cl^- corrosion stemming from the MnO_x protective film. Hence, MnO_x/NiFe-LDH/NF can act as a promising OER electrocatalyst for alkalized natural seawater electrolysis.

Crude Glycerol as a Potential Feedstock for Future Energy via Thermochemical Conversion Processes: A Review

Biodiesel is an emerging substitute for petroleum-based products. It is considered an ecologically safe and sustainable fuel. The high cost of biodiesel production is linearly related to its feedstock. Crude glycerol, which is a by-product of the biodiesel industry, is also a major challenge that must be addressed. A large volume of crude glycerol needs to be disposed of, and this involves processing, dumping, and land requirements. This increases the cost of biodiesel production. One way to decrease the cost of biodiesel production is to utilize its by-product to make valuable products. Crude glycerol can be processed to produce a variety of chemicals and products. The present utilization of crude glycerol is not enough to bring down its surplus availability. Thermochemical conversion processes can utilize crude glycerol as a starting feedstock and convert it into solid, liquid, and gaseous fuels. The utilization of crude glycerol through integrated thermochemical conversion processes could lead to an integrated biorefinery. This review paper highlights the research scope for areas where crude glycerol could be utilized as a feedstock or co-feedstock in thermochemical conversion technology. Various thermochemical conversion processes, namely, gasification, pyrolysis, combustion, catalytic steam reforming, liquefaction, and supercritical water reforming, are discussed and shown to be highly suitable for the use of crude glycerol as an economical feedstock. It is found that the integration of crude glycerol with other thermochemical conversion processes for energy production is a promising option to overcome the challenges related to biodiesel production costs. Hence, this paper provides all the necessary information on the present utilization status of crude glycerol in thermochemical conversion processes, as well as identifying possible research gaps that could be filled by future research studies.

Selective CO2 Conversion into Fuels on Nanochannels

The purpose of this research idea is to develop a method to electrochemically convert carbon dioxide into higher alcohol chains such as ethanol to be used as fuel. Electrochemical CO₂ reduction has low yields and poor product selectivity, being able to improve this reaction would have an impact in the energy and food market. We propose the use of a modified nanofluidic transistor to block reaction steps that are thermodynamically favored by constraining the kinetics of the reaction when the reaction takes place in a geometrically restricted environment with different double layer properties to those found in conventional planar electrosynthesis.

A Porous Cobalt (II) Metal⁻Organic Framework with Highly Efficient Electrocatalytic Activity for the Oxygen Evolution Reaction

A 3D porous framework ([Co_1.5(tib)(dcpna)]·6H₂O) (1) with a Wei topology has been synthesized by solvothermal reaction of 1,3,5-tris(1-imidazolyl)-benzene (tib), 5-(3′,5′-dicarboxylphenyl)nicotinic acid (H₃dcpna) and cobalt nitrate. The electrocatalytic activity for water oxidation of 1 has been investigated in alkaline solution. Compound 1 exhibits good oxygen evolution reaction (OER) activities in alkaline solution, exhibiting 10 mA·cm⁻² at η = 360 mV with a Tafel slope of 89 mV·dec⁻¹. The high OER activity can be ascribe to 1D open channels along b axis of 1, which expose more activity sites and facilitate the electrolyte penetration.

Co/Mo bimetallic addition to electrolytic manganese dioxide for oxygen generation in acid medium

An efficient electrocatalyst comprising inexpensive and earth-abundant materials for the oxygen evolution reaction (OER) is crucial for the development of water electrolysis. In this work, in-situ addition of cobalt/molybdenum ions to the electrolytic manganese dioxide has been shown to be beneficial for the OER in acid solution as its overpotential performed better (305 mV) than that of the commercial DSA^® (341 mV) at 100 mA cm⁻². The OER was investigated at ambient temperature in 2 M H₂SO₄ solution on the modified EMD (MnMoCoO) electrodes. The energy efficiency of the MnMoCoO electrodes improved significantly with the amount of Co in the plating solution. For the electrodeposited catalysts, physico-chemical and electrochemical measurements were conducted including static overpotentials. The better performance of the modified EMD was attributed to an improved charge transfer resistance (R_ct; 0.290 Ω cm²), average roughness factor (r_f; 429) and decrease in water content in the electrodeposited catalysts. The kinetic parameters obtained on MnMoCoO catalysts were compared and discussed according to the cobalt concentration.

Electrolytic manganese dioxide (EMD): a perspective on worldwide production, reserves and its role in electrochemistry

EMD – a weird but played wonderful role in electrochemistry and its intercalation mechanism suitable for alkaline rechargeable batteries and supercapacitors.