A tin (Sn) nanostructure has been applied to a gas diffusion electrode for the direct electro-reduction of carbon dioxide (CO 2 ) in a zero-gap electrolytic cell. A Sn catalyst layer was evenly ...applied to a carbon substrate by a controlled spraying technique and the efficient catalytic conversion of gas-phase CO 2 to formic acid (HCOOH) demonstrated. We observed that the overall mean faradaic efficiency towards HCOOH remained above 5.0% over the entire reduction time. In addition, due to its compact configuration and surroundings at near ambient conditions the approach described is promising in both modularity and scalability. Sustainable energy sources such as solar, wind, or geothermal electricity could be used as a power source to minimize the large-scale operating cost.
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•Ethanol assisted water electrolysis reduces electric energy input by more than 50%.•Partial oxidation of ethanol leads to formation of undesired chemicals.•Degradation occurs due to ...formation of by-products and poisoning of catalyst.•Better catalyst has the potential to increase ethanol to H2 conversion efficiency.•A plausible ethanol electro-oxidation mechanism has been proposed
The global interest in hydrogen/fuel cell systems for distributed power generation and transport applications is rapidly increasing. Many automotive companies are now bringing their pre-commercial fuel cell vehicles in the market, which will need extensive hydrogen generation, distribution and storage infrastructure for fueling of these vehicles. Electrolytic water splitting coupled to renewable sources offers clean on-site hydrogen generation option. However, the process is energy intensive requiring electric energy >4.2kWh for the electrolysis stack and >6kWh for the complete system per m3 of hydrogen produced. This paper investigates using ethanol as a renewable fuel to assist with water electrolysis process to substantially reduce the energy input. A zero-gap cell consisting of polymer electrolyte membrane electrolytic cells with Pt/C and PtSn/C as anode catalysts were employed. Current densities up to 200mAcm−2 at 70°C were achieved at less than 0.75V corresponding to an energy consumption of about 1.62kWhm−3 compared with >4.2kWhm−3 required for conventional water electrolysis. Thus, this approach for hydrogen generation has the potential to substantially reduce the electric energy input to less than 40% with the remaining energy provided by ethanol. However, due to performance degradation over time, the energy consumption increased and partial oxidation of ethanol led to lower conversion efficiency. A plausible ethanol electro-oxidation mechanism has been proposed based on the Faradaic conversion of ethanol and mass balance of the by-products identified and quantified using 1H nuclear magnetic resonance spectroscopy and gas chromatography.
The tin (Sn) based gas diffusion electrode was fabricated and applied for CO₂ electroreduction in a zero gap cell. The fabrication was done by electrodeposition from a simple citrate–chloride plating ...solution by chronoamperometric method. The electrode showed good stability during CO₂ reduction even though the conversion of CO₂ into formate reached only 18% faradaic efficiency during the initial 5 min and maintained about 12% until the end of the reduction time of 1 h.
Hydrogen has the potential to play an important role in decarbonising our energy systems. Crucial to achieving this is the ability to produce clean sources of hydrogen using renewable energy sources. ...Currently platinum is commonly used as a hydrogen evolution catalyst, however, the scarcity and expense of platinum is driving the need to develop non-platinum-based catalysts. Here we report a protein-based hydrogen evolution catalyst based on a recombinant silk protein from honeybees and a metal macrocycle, cobalt protoporphyrin (CoPPIX). We enhanced the hydrogen evolution activity three fold compared to the unmodified silk protein by varying the coordinating ligands to the metal centre. Finally, to demonstrate the use of our biological catalyst, we built a proton exchange membrane (PEM) water electrolysis cell using CoPPIX-silk as the hydrogen evolution catalyst that is able to produce hydrogen with a 98% Faradaic efficiency. This represents an exciting advance towards allowing protein-based catalysts to be used in electrolysis cells.
A new type of a high temperature liquid metal-air energy storage cell based on solid oxide electrolyte has been successfully demonstrated at 750 ℃ by feeding metal Sn. In order to understanding the ...initial size effect of metal as a liquid fuel, we report here the impact of the thermal and electrochemical oxidation behavior of nano Sn （-100 nm）, comparing with micro-sized （-5 μm） and macro-sized （4350 μm） Sn. The thermogravimetric analysis and the monitoring OCV test indicate that the distinct property of nano-sized Sn results in a favorable thermal oxidation behavior near the melting point and a promising power performance due to enhanced fuel transport to the anode. However, the accumulated Sn oxide at the reaction interface during a discharge test towards the limitation of further electrochemical oxidation.
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•Carbon/hydrocarbon assisted water electrolysis reviewed for clean hydrogen production.•Reviewed different electrochemical technologies using carbon fuels under development.•This ...technology has been progressed to different levels of maturity for different carbon sources.•This route of hydrogen production can lower the electric input and CO2 emissions from the carbon sources.
Hydrogen is mainly produced by natural gas reforming, which is a highly efficient process with low feedstock costs. However, the rising interest in clean technologies will increase the demand for hydrogen, meaning that other sources will need to be explored. Although coal is currently the major source of power generation, its demand appears to be declining due to the rise in electricity generated from renewable energy sources and the worldwide quest for low-emission power generation. Coal reserves worldwide are abundant, but new technologies would be needed to produce hydrogen from this feedstock. Coal gasification is one well-established technology for this purpose, but it is inefficient and produces high CO2 emissions. An alternative technology that has been investigated over the past few decades is carbon assisted water electrolysis. The basic process is water/steam electrolysis, with part of the energy required for the electrolysis provided by the chemical energy of coal, which reduces the overall electrical energy input. In addition to coal, the process can also use other carbon sources, such as biomass, alcohols or gaseous hydrocarbons. Several studies have investigated this electrochemical route of hydrogen production, employing different electrolytes in a wide temperature range (room temperature to 850 °C) under different process conditions. This paper presents a comprehensive review of carbon assisted water electrolysis, associated materials used and the challenges for the development of the technology at the commercial scale.
수송/저장용 수소 생산 확대를 위한 암모니아의 안전 위험 관리 표준 동향 주형국(HyungKuk Ju); 이혁주(Hyeokjoo Lee); 이창현(Chang Hyun Lee) ...
Biuletyn Uniejowski,
2023, Letnik:
56, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Ammonia, which is closely related to our lives, has a significant impact on our lives as a representative substance for crop cultivation. Recently, it has gained attention as an efficient and ...productive hydrogen/storing substance that can replace fossil fuels. Efforts are being made to utilize it as a renewable energy source through thermochemical and electrochemical reactions. However, the use of ammonia, which encompasses the era, carries inherent toxicity, so a comprehensive understanding of ammonia safety is necessary. To ensure safety in the transportation and storage of ammonia and chemical substances domestically and internationally, national and organizational standards are being developed and provided through documents and simple symbols to help people understand. This review explores the chemical characteristics of ammonia, its impact on human health, and the global trends in safety standards related to ammonia. Through this examination, the paper aims to contribute to the discourse on the safety and risk management of ammonia transport and storage, crucial for achieving carbon neutrality and expanding the hydrogen economy.
Electrochemical nitrogen reduction reaction (NRR) under ambient conditions has attracted considerable scientific and engineering interest as a green alternative route for NH3 production. Molybdenum ...is a promising candidate as an electrocatalyst for NRR as it has a suitable binding strength with N species. However, the design of an efficient Mo‐based catalyst remains elusive. To enhance the selectivity of NRR toward NH3, we have developed a carbon nanofiber catalyst embedded with molybdenum and cobalt (Co−Mo−CNF). Co with a strong ability to dissociate water enhances local proton source near Mo, where the hydrogenation step of the NRR occurs. A NH3 formation rate of 72.72 μg h−1 mg−1 and a Faradaic efficiency of 34.5 % were obtained at −0.5 V vs. RHE. We also attempted to provide a mechanistic understanding of the NRR via in situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) and isotopic labeling experiments using 15N2 and D2O.
The appropriate amount of water adsorbed on the surface of Co−Mo co‐embedded carbon nanofibers facilitated the formation of N−H bonds and promoted the protonation step of nitrogen reduction via proton source transfer from the water dissociation, which was confirmed by the results of in situ surface‐enhanced infrared absorption spectroscopy experiments and isotopic labeling experiments using D2O and 15N2.
Carbon supports enable Pt electrocatalyst to offer a better electrocatalytic activity and an efficient catalyst utilization in polymer electrolyte membrane fuel cells (PEMFCs). Highly graphitized ...carbon structure has been regarded as an active and durable catalyst support due to its high electronic conductivity and corrosion tolerant property. However, the graphitized carbon supported Pt nanoparticles may not directly correlate with a high electrochemical surface active area and electrocatalyst utilization due to the collapse of the support pore structure and Pt catalyst agglomeration. To solve this challenge, herein, we apply two different graphitization methods (thermal and catalytic graphitizations) on electrospun carbon nanofibers, which successfully control the pore structure distribution and thereby improve the utilization of Pt electrocatalyst on fibrous graphitized carbon supports. The enhanced performance of our synthesized Pt catalyst on new carbon support was investigated by the activity for oxygen reduction reaction and the corrosion tolerance using a start-up/shut-down accelerated stress test. The influence of the degree of graphitization and the proportion of the controlled meso/macroporous structures have further evaluated in a single cell system where has achieved the maximum power density of 0.85 W cm−2 due to its enhanced mass transport at high current density region.
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•Fabrication of meso/macroporous graphitized carbon nanofiber via electrospinning.•Catalytically graphitized CNF support showing high corrosion tolerance.•Improved fuel cell performance with unique meso/macroporous structured Pt catalyst.
A novel method to create a high-density nanopore structure between the neighboring pores of anodic alumina template is developed via applying a simple consecutive three-step anodization process. As a ...demonstration, the nanostructure comprising more numbers of individually addressable Pd nanorods was utilized to enhance the electrocatalysis of ethanol in alkaline media, which is due to a dramatic increment in surface reactive sites.
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