Enhanced Stability and Catalytic Activity on Layered Perovskite Anode for High-Performance Hybrid Direct Carbon Fuel Cells

In this work, we investigate a novel A-site ordered layered perovskite oxide, (PrBa)_0.95Fe_1.8-xCu_xNb_0.2O_5+δ (PBFCN), as an anode material for hybrid direct carbon fuel cells (HDCFCs). We study the effect of anode composition on the electrochemical performance of HDCFCs. The electrolyte-supported single cell with (PrBa)_0.95Fe_1.4Cu_0.4Nb_0.2O_5+δ (PBFCu_0.4N) anode achieves the highest peak power density of 431 mW cm^-2 at 800 °C with activated carbon as the fuel. Moreover, a power generation unit is also made to demonstrate the practical utilization of PBFCN, which delivers a peak power of 0.51 W at 800 °C without any carrier gas, and a small fan can operate for more than 10 h by using the as-fabricated HDCFC as a power generation unit. The PBFCN anode achieves greatly enhanced catalytic activity by improving the chemical adsorption and electrochemical oxidation of CO at the anode/CO interface, which is mainly due to the high-activity Cu ions in PBFCN. The inactive element Nb doping and ordered layered structure endow the material with excellent redox structural stability. The present study provides a new idea for the design and development of high-performance anode materials for HDCFCs applications.

CO2 neutral fuels

CO2 is a valuable resource, life on Earth depends on it. Rather than wasting it to the atmosphere, or burying it underground, CO2 can be combined with water and turned into valuable chemicals and fuels, the process being powered by renewable electricity. Renewable electricity generated by wind and photovoltaics (PV) is making big strides, but is limited by ill-matched supply and demand. In addition, electricity only makes up 20% to 30% of total energy demand. Domestic heating, high temperature/pressure Industrial processes and mobility/transportation gobble up the rest. Mobility and transportation prove particularly difficult to decarbonise. Aviation is a case in point. Battery-powered aircraft are unlikely to become feasible by 2050. Hydrogen has too low an energy density and is haunted by safety issues. Current policy, therefore, is directed at bio fuels. One problem, there is not enough of it. The Fuel vs. Food vs. Flora trilemma of bio-based fuel is unlikely to gain public acceptance. By converting renewable electricity into fuel, power to molecules (P2M), two birds are killed with one stone: providing fuel for long haul transportation and enabling long-term, large-scale energy storage to cover the seasonal mismatch between supply and demand of renewable electricity. Feedstock consists of air-captured carbon or nitrogen and water. Chemically combined, it creates a liquid fuel with greatly enhanced energy density, such as kerosene or ammonia, or gaseous fuel like methane which can replace natural gas in the existing gas network. Direct air capture of CO2 is currently being commercialised. The conversion technology of water and CO2 by electrolysis has recently been extended to novel plasma technology, the sub ject of this paper. For CO2 splitting by plasmolysis, the reduced electric field has been identified as the key parameter explaining and improving the energy efficiency. Energy efficiency by plasmolysis is similar to that of electrolysis, but offers advantages in energy density, upscaling and switching in response to intermittent power with no use of scarce material. A simple model explains the inverse relation between energy efficiency and particle conversion and relates input microwave power to CO2 gas density, plasma dimension and ionisation degree, allowing design parameters for a 100 kW pilot reactor to be specified. Recycling CO2 in combination with P2M is a game-changing technology to meet overall CO2 emission reduction targets. It takes advantage of existing, inexpensive infrastructure for energy storage, transport and distribution. Existing internal combustion engine technology can be maintained where necessary. Close coupled to a remote solar array or an off-shore wind farm it offers a solution to decentralised renewable fuel production at the renewable electricity source.

A perspective on liquid salts for energy and materials

Liquid salts comprising molten salts and ionic liquids offer important media to address both energy and materials challenges. Here we review topics presented in this Faraday Discussion volume related to improved electrowinning of metals, optimisation of processes, new electrochemical device concepts, chemistry in ionic liquids, conversion of biomass, carbon chemistry and nuclear applications. The underlying phenomenology is then reviewed and commentary given. Some future applications are then discussed, further exemplifying the high potential rewards achievable from these chemistries.

Molten salts and energy related materials

Molten salts have been known for centuries and have been used for the extraction of aluminium for over one hundred years and as high temperature fluxes in metal processing. This and other molten salt routes have gradually become more energy efficient and less polluting, but there have been few major breakthroughs. This paper will explore some recent innovations that could lead to substantial reductions in the energy consumed in metal production and in carbon dioxide production. Another way that molten salts can contribute to an energy efficient world is by creating better high temperature fuel cells and novel high temperature batteries, or by acting as the medium that can create novel materials that can find applications in high energy batteries and other energy saving devices, such as capacitors. Carbonate melts can be used to absorb carbon dioxide, which can be converted into C, CO and carbon nanoparticles. Molten salts can also be used to create black silicon that can absorb more sunlight over a wider range of wavelengths. Overall, there are many opportunities to explore for molten salts to play in an efficient, low carbon world.