Studies on polymer modified metal oxide anode for oxygen evolution reaction in saline water

Enhancement of the Green H2 Production by Using TiO2 Composite Polybenzimidazole Membranes

This study reports the hydrogen production using TiO2 based composite polybenzimidazole membranes through the SO2 depolarized electrolysis that requires lower energy input than the direct water electrolysis. Composite membranes prepared and studied in this work showed very promising results in terms of proton conductivity, chemical stability, and crossover. Thus, a reduction in SO2 crossover was observed with the increase of the concentration of TiO2, obtaining reductions as high as 42% with the 3.0 wt% TiO2-PBI membrane at 120 °C. Higher hydrogen production rates and Faradaic efficiencies were achieved by all the composite membranes, with an optimum for the 1.0 wt% TiO2-PBI membrane (with this membrane, the production of hydrogen increased a 53% at 110 °C and a 49% at 120 °C as compared with the standard PBI membrane), demonstrated the benefit of the use of composite membranes with respect to the standard one for green hydrogen production.

Recent Advances in Seawater Electrolysis

Hydrogen energy, as a clean and renewable energy, has attracted much attention in recent years. Water electrolysis via the hydrogen evolution reaction at the cathode coupled with the oxygen evolution reaction at the anode is a promising method to produce hydrogen. Given the shortage of freshwater resources on the planet, the direct use of seawater as an electrolyte for hydrogen production has become a hot research topic. Direct use of seawater as the electrolyte for water electrolysis can reduce the cost of hydrogen production due to the great abundance and wide availability. In recent years, various high-efficiency electrocatalysts have made great progress in seawater splitting and have shown great potential. This review introduces the mechanisms and challenges of seawater splitting and summarizes the recent progress of various electrocatalysts used for hydrogen and oxygen evolution reaction in seawater electrolysis in recent years. Finally, the challenges and future opportunities of seawater electrolysis for hydrogen and oxygen production are presented.

Advanced Electrocatalysis for Energy and Environmental Sustainability via Water and Nitrogen Reactions

Clean and efficient energy storage and conversion via sustainable water and nitrogen reactions have attracted substantial attention to address the energy and environmental issues due to the overwhelming use of fossil fuels. These electrochemical reactions are crucial for desirable clean energy technologies, including advanced water electrolyzers, hydrogen fuel cells, and ammonia electrosynthesis and utilization. Their sluggish reaction kinetics lead to inefficient energy conversion. Innovative electrocatalysis, i.e., catalysis at the interface between the electrode and electrolyte to facilitate charge transfer and mass transport, plays a vital role in boosting energy conversion efficiency and providing sufficient performance and durability for these energy technologies. Herein, a comprehensive review on recent progress, achievements, and remaining challenges for these electrocatalysis processes related to water (i.e., oxygen evolution reaction, OER, and oxygen reduction reaction, ORR) and nitrogen (i.e., nitrogen reduction reaction, NRR, for ammonia synthesis and ammonia oxidation reaction, AOR, for energy utilization) is provided. Catalysts, electrolytes, and interfaces between the two within electrodes for these electrocatalysis processes are discussed. The primary emphasis is device performance of OER-related proton exchange membrane (PEM) electrolyzers, ORR-related PEM fuel cells, NRR-driven ammonia electrosynthesis from water and nitrogen, and AOR-related direct ammonia fuel cells.

Studies on Influence of Cell Temperature in Direct Methanol Fuel Cell Operation

Directmethanol fuel cells (DMFCs) offer one of the most promising alternatives for the replacement of fossil fuels. A DMFC that had an active Membrane Electrode Assembly (MEA) area of 45 cm2, a squoval-shaped manifold hole design, and a Pt-Ru/C catalyst combination at the anode was taken for analysis in simulation and real-time experimentation. A mathematical model was developed using dynamic equations of a DMFC. Simulation of a DMFC model using MATLAB software was carried out to identify the most influencing process variables, namely cell temperature, methanol flow rate and methanol concentration during a DMFC operation. Simulation results were recorded and analyzed. It was observed from the results that the cell temperature was the most influencing process variable in the DMFC operation, more so than the methanol flow rate and the methanol concentration. In the DMFC, real-time experimentation was carried out at different cell temperatures to find out the optimum temperature at which maximum power density was obtained. The results obtained in simulation and the experiment were compared and it was concluded that the temperature was the most influencing process variable and 333K was the optimum operating temperature required to achieve the most productive performance in power density of the DMFC.

Role of Organic Components in Electrocatalysis for Renewable Energy Storage

Carbon dioxide electroreduction and water splitting are known as two promising strategies to convert renewable intermittent electrical energy into chemical energy. Thus, the three half-reactions, namely, CO₂ reduction reaction, hydrogen evolution reaction, and the oxygen evolution counter reaction, in these two electrolytic processes have attracted wide research interest. Organic polymer electrocatalysts or electrocatalysts containing organic components play important roles in these catalytic processes. It has been shown that the organic molecules can efficiently catalyze the reactions themselves, and modulate the active sites towards high selectivity and efficiency. The roles of the organic molecules in conducting polymers, the metal complexes, and the framework materials are extracted for the three half-reactions mentioned above, and this comprehensive review will serve as a guide for future research and aid in the design of electrocatalysts related to organic molecules.

Cobalt sulfide aerogel prepared by anion exchange method with enhanced pseudocapacitive and water oxidation performances

This work introduces the anion exchange method into the sol-gel process for the first time to prepare a metal sulfide aerogel. A porous Co₉S₈ aerogel with a high surface area (274.2 m² g^-1) and large pore volume (0.87 cm³ g^-1) has been successfully prepared by exchanging cobalt citrate wet gel in thioacetamide and subsequently drying in supercritical ethanol. Such a Co₉S₈ aerogel shows enhanced supercapacitive performance and catalytic activity toward oxygen evolution reaction (OER) compared to its oxide aerogel counterpart. High specific capacitance (950 F g^-1 at 1 A g^-1), good rate capability (74.3% capacitance retention from 1 to 20 A g^-1) and low onset overpotential for OER (220 mV) were observed. The results demonstrated here have implications in preparing various sulfide chalcogels.

Fuel Production from Seawater and Fuel Cells Using Seawater

Seawater is the most abundant resource on our planet and fuel production from seawater has the notable advantage that it would not compete with growing demands for pure water. This Review focuses on the production of fuels from seawater and their direct use in fuel cells. Electrolysis of seawater under appropriate conditions affords hydrogen and dioxygen with 100 % faradaic efficiency without oxidation of chloride. Photoelectrocatalytic production of hydrogen from seawater provides a promising way to produce hydrogen with low cost and high efficiency. Microbial solar cells (MSCs) that use biofilms produced in seawater can generate electricity from sunlight without additional fuel because the products of photosynthesis can be utilized as electrode reactants, whereas the electrode products can be utilized as photosynthetic reactants. Another important source for hydrogen is hydrogen sulfide, which is abundantly found in Black Sea deep water. Hydrogen produced by electrolysis of Black Sea deep water can also be used in hydrogen fuel cells. Production of a fuel and its direct use in a fuel cell has been made possible for the first time by a combination of photocatalytic production of hydrogen peroxide from seawater and dioxygen in the air and its direct use in one-compartment hydrogen peroxide fuel cells to obtain electric power.

Solid State Sensor for Simultaneous Measurement of Total Alkalinity and pH of Seawater

A novel design is demonstrated for a solid state, reagent-less sensor capable of rapid and simultaneous measurement of pH and Total Alkalinity (A_T) using ion sensitive field effect transistor (ISFET) technology to provide a simplified means of characterization of the aqueous carbon dioxide system through measurement of two "master variables": pH and A_T. ISFET-based pH sensors that achieve 0.001 precision are widely used in various oceanographic applications. A modified ISFET is demonstrated to perform a nanoliter-scale acid-base titration of A_T in under 40 s. This method of measuring A_T, a Coulometric Diffusion Titration, involves electrolytic generation of titrant, H⁺, through the electrolysis of water on the surface of the chip via a microfabricated electrode eliminating the requirement of external reagents. Characterization has been performed in seawater as well as titrating individual components (i.e., OH^-, HCO₃^-, CO₃^2-, B(OH)₄^-, PO₄^3-) of seawater A_T. The seawater measurements are consistent with the design in reaching the benchmark goal of 0.5% precision in A_T over the range of seawater A_T of ∼2200-2500 μmol kg^-1 which demonstrates great potential for autonomous sensing.

Freeze-dried MoS2 sponge electrodes for enhanced electrochemical energy storage

High surface area MoS₂ sponge electrodes were synthesized via a facile hydrothermal method followed by a freeze drying process and showed high specific capacitance and better charge storage behavior.

Eco-friendly and facilely prepared silica modified amorphous titania (TiO2–SiO2) electrocatalyst for the O2 and H2 evolution reactions

A silica modified amorphous titania (TiO₂–SiO₂) electrocatalyst was prepared by a simple, cheap, and scalable preparation procedure. The catalyst is active in the oxygen and hydrogen evolution reactions, leading to a promising bifunctional electrocatalyst.

Selective sorption of palladium by thiocarbamoyl-substituted thiacalix[n]arene derivatives immobilized on amberlite resin: application to leach liquors of automotive catalysts

Thiocarbamoyl-substituted thiacalix[n]arene derivatives immobilized on amberlite resins have the potential for application as new adsorbents for selective separation of Pd(ii) ions from leach liquors of automotive catalysts.