Efficient electrochemical hydrogenation (ECH) of organic compounds is essential for sustainability, promoting chemical feedstock circularity and synthetic fuel production. Yet in bio-oil, phase separation in aqueous media restricts ECH to the aqueous fraction and leaves the hydrophobic oily phase comparatively inaccessible. Herein, we test whether methanol catholytes can directly engage the hydrophobic oily phase of pinewood and wheat-straw pyrolysis oils in an H-type cell. Using a PtRu/ACC cathode with NaCl or TBAHFP dosed by mass, we tracked composition as internal-standard-normalised GC-MS responses with qualitative FTIR support and assessed cathode condition by SEM/EDS. Phenolic responses decreased preferentially; FTIR indicated reduced aromatic character with condition-dependent O-H and aliphatic C-H envelopes, and additive choice set a trade-off with surface condition. This paper establishes chemical tractability of oily-phase ECH in methanol under mild conditions and identifies additive-dependent degradation as a dominant practical constraint.

Solid Oxide Fuel Cells (SOFCs) are a highly efficient energy conversion technology, but the degradation of metal interconnects remains a critical challenge. Conventional coatings often lack sufficient electrochemical performance and stability. In this study, a dense Ag coating was developed using the screen-printing method to improve the electrochemical performance and chemical compatibility of SOFC interconnects. Symmetric and single cells were prepared with La0.6Sr0.4Co0.2Fe0.8O3-delta cathodes and SUS430 interconnects to evaluate the coating under high-temperature conditions, simulating real SOFC operation. The Ag coating demonstrated excellent adhesion, uniformity, and oxidation resistance, with conductivity increasing from 0.01 to 13.13 S cm(-1) at 650 degrees C after coating and the area-specific resistance decreasing from 1.843 to 0.378 ohm cm(2) after coating between cathode and interconnect at 750 degrees C. Moreover, the coating effectively inhibited Cr diffusion from the interconnect to the cathode, addressing a major limitation in SOFC durability. These results suggest that Ag coatings offer a practical and promising solution to enhance the performance and extend the lifespan of SOFC systems.

Ferritic stainless steel (FSS) is widely used as an interconnect material in solid oxide cells (SOCs). However, these interconnects degrade faster under simultaneous exposure to oxidizing and reducing atmospheres, a phenomenon known as the dual atmosphere effect. This study used SUS430 to investigate the mechanisms behind this effect. Oxidation behavior was compared for single air atmosphere, and dual atmosphere at 750 degrees C after 50, 100, and 200 h. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed significant hydrogen enrichment at grain boundaries after 200 h in the dual atmosphere exposure as compared to the single atmosphere. To explore hydrogen's role, first-principles calculations were performed evaluating its adsorption energy on the (110) Fe-Cr crystal plane and its impact on Cr diffusion. The results revealed that hydrogen's presence raises the energy barrier for Cr diffusion and alters its pathway. This suggests that hydrogen enrichment at grain boundaries is a major factor in the dual atmosphere effect, as it hinders Cr diffusion, contributing to accelerated degradation of interconnect materials.

Efficient electrochemical hydrogenation (ECH) of organic compounds is essential for sustainability, promoting chemical feedstock circularity and synthetic fuel production. This study investigates the ECH of benzoic acid, phenol, guaiacol, and their mixtures, key components in upgradeable oils, using a carbon-supported PtRu catalyst under varying initial concentrations, temperatures, and current densities. Phenol achieved the highest conversion (83.17%) with a 60% Faradaic efficiency (FE). In mixtures, benzoic acid + phenol yielded the best performance (64.19% conversion, 74% FE), indicating a synergistic effect. Notably, BA consistently exhibited 100% selectivity for cyclohexane carboxylic acid (CCA) across all conditions. Density functional theory (DFT) calculations revealed that parallel adsorption of BA on the cathode (-1.12 eV) is more stable than perpendicular positioning (-0.58 eV), explaining the high selectivity for CCA. These findings provide a foundation for future developments in ECH of real pyrolysis oil.

The EU has made the commitment to reduce pollutant gases emissions by 2030 and achieve climate neutrality by 2050. To achieve these targets the power generation sector must engage. Gas turbines will play a part through the use of alternative fuels such as H2. However the adoption of H2 as a fuel presents multiple engineering challenges, from flame stability, to NOx emissions, to materials’ degradation. The latter is inherently linked to the technologies used to produce hydrogen in the bulk quantities required. Different technologies will generate H2 with differing quantities and types of contaminants (i.e., Cl-based for seawater electrolysis, S-based from steam methane reforming). This is important as, upon combustion, these contaminants can form harmful species in the exhaust stream, linked to mechanisms causing materials degradation. It is therefore crucial to understand the types of contaminants that are present in bulk H2 and so in the combusted gases. This work links together fuel and ingested air chemistry in the gas turbines to the chemical composition of the combusted gases, to the degradation mechanism that might arise in blading materials, and finally their impact on the gas turbine life. Exhaust gas composition has been predicted via thermodynamic modelling, and the condensation of harmful species that will ultimately dictate the corrosion mechanisms (e.g., alkali vapour) calculated.

This study explores the emergence of oxidation-resistant alloys as potential replacements for traditional ceramics in Solid Oxide Fuel Cells (SOFCs), specifically Ferritic Stainless Steel (FFS). Despite its promise, FFS encounters challenges such as oxidation and corrosion. Most research on FFS interconnect damage has primarily focused on high-temperature oxidation in single atmospheres. However, in practice, the interconnect is exposed to both oxidizing and reducing atmospheres concurrently, leading to enhanced oxidation known as the dual atmosphere effect. The significance of this phenomenon is increasingly recognized by researchers and industry experts, yet understanding its implications for FFS degradation and protective measures remains a young discipline. This article provides an overview of the oxidation mechanisms of FSS under various conditions, proposed mechanisms, and potential protective strategies to address the effects of the dual atmosphere.

In pursuit of cleaner and more sustainable power generation, gas turbine power cycles using supercritical carbon dioxide (sCO 2 ) as a working fluid have emerged as an option to meet emissions targets. The Allam cycle achieves emission reduction through high-pressure sCO 2 in an oxy-combusted, highly recuperated cycle, operating at 300 bar and up to 800°C. Alloy 625, known for its high corrosion resistance, is used for high-temperature components, including heat exchangers, which can be manufactured traditionally or via additive manufacturing (AM) techniques, such as laser powder bed fusion (LPBF).This study investigates Alloy 625’s microstructural influence on resistance to simulated Allam cycle conditions; comparing as-built and solution heat-treated LPBF AM samples with conventionally manufactured wrought. Isothermal oxidation tests were conducted at 800 ° C for 1000h in a CO 2 rich environment (CO 2 + 2.7mol% H 2 O + 1.43mol% N 2 + 0.17mol% O 2 + 300ppm SO 2 ). Wrought Alloy 625 demonstrated the lowest oxidation rate, attributed to its homogenized microstructure and fine grain size. Solution heat-treated AM samples exhibited a continuous oxide layer due to grain boundary changes, enhancing oxide scale formation. The K p values of as-built, solution heat-treated and wrought Alloy 625 were 4.8 x 10 − 5 , 5.3×10 − 5 , and 4.0×10 − 5 mg 2 /cm 4 respectively.Grain morphology and heat treatment influenced oxidation. As-built LPBF samples formed ridges on the oxide scale and with subsurface voids, while wrought samples displayed uniform oxide layers without subsurface voids. These findings highlight how manufacturing techniques and post-processing affect Alloy 625’s high-temperature performance, crucial for turbine casing and heat exchangers in a baseline Allam cycle environment.

Electrochemical hydrogenation (ECH) is a sustainable alternative to traditional hydrogenation methods, offering selective reduction of organic compounds under mild conditions. This study investigates the co-hydrogenation of benzoic acid (BA) and phenol on a platinum-ruthenium on activated carbon cloth (PtRu/ACC) catalyst, with a focus on the synergistic effects arising from hydrogen bonding. Density Functional Theory (DFT) calculations reveal that the formation of a hydrogen-bonded complex between BA and phenol facilitates adsorption energy and lowers activation barrier energies compared to BA alone. Experimental results demonstrate that a 20 mM BA and 5 mM phenol mixture achieves the highest conversion rate (87.33%) and faradaic efficiency (63%), significantly outperforming single-compound systems. Notably, co-hydrogenation facilitates the reduction of BA to cyclohexanemethanol, a valuable product for biofuel applications, which has reduced corrosiveness and improved energy density. These findings underscore the potential for optimising multi-compound ECH systems through targeted catalyst design and reagent concentration tuning, thus advancing the development of efficient strategies for bio-oil upgrading and sustainable chemical production.

The commercial deployment of aqueous zinc-ion batteries (AZIBs) is hampered by dendrites, the hydrogen evolution reaction (HER), and corrosion reactions. To tackle these challenges, we have introduced 3,3′-dithiobis-1-propanesulfonic acid disodium salt (SPS), a symmetrical sulfur-based organic salt, as an electrolyte additive for AZIBs. Unlike conventional electrolyte additives that favor (002) deposition, SPS enables dense (100) growth through a unique symmetrically aligned concentration-controlled adsorption network, affording structural uniformity and compactness to the Zn deposit layer. The dual-action symmetrical SPS additive adsorbs onto the Zn surface via vicinal sulfur atoms, blocking electrolyte access to the Zn anode, enhancing the transportation kinetics of Zn 2+ , and simultaneously promoting desolvation by displacing water molecules from the solvation shell. This synergistic effect improves the stability of the Zn anode by mitigating HER and corrosion, resulting in over 1100 h of cycling at 5 mA cm −2 , 5 mAh cm −2 , stable operation at even 15 mA cm −2 , 15 mAh cm −2 , and achieving impressive Coulombic efficiency (CE) of 99.41%. As validation, the Zn/NaV 3 O 8 ·1.35H 2 O cell with SPS-additive afforded high cycling stabilization and excellent capacity retention of 95.5%. This study offers valuable insights for advancing AZIBs and other metal-based batteries.

The use of fossil fuels has caused adverse effects, notably carbon emissions and climatic change. Thermal energy storage (TES) systems can be used to store energy and, when integrated with CSP, can help mitigate the intermittency of renewable sources. Higher TES working temperatures correspond to higher efficiencies which may lower costs. Various substances have been proposed as TES media; molten salts (MS) emerge as one of the most attractive options due to their stability at high temperatures. However, they can accelerate corrosion on materials, and therefore, compatibility between materials and media is crucial. Additionally, the impact of MS on welds (or welded components) has received less attention than for parent material. To address this research gap, this study compares the corrosion behaviour of plain and welded SS316L and SS304L in a mixture of 10NaNO378KNO3-12KCl mol% at 600 degrees C for up to 500 h. The samples were analysed by dimensional metrology (DM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Dimensional metrology shows a higher metal loss and sound metal loss for SS304L than SS316L. SEM micrographs showed the formation of non-adherent corrosion products on alloys surfaces. The EDS shows a selective dissolution of Fe and Cr, along with Na, K and Cl penetration into the alloy. Comparing the results, the welded areas experienced higher metal loss as compared to plain alloy samples. Another key observation was that the SS304L samples displayed lower overall corrosion resistance than SS316L.

Efficient and selective electrochemical hydrogenation (ECH) of organic compounds is crucial for global sustainability; offering both chemical feedstock circularity and routes to generate synthetic fuels, reducing fossil fuel reliance. This study focuses on ECH of benzoic acid (BA), phenol (P), and guaiacol (G), commonly appearing as mixtures in potential oils for upgrade. The impact of various conditions on the hydrogenation process was elucidated using a carbon-supported PtRu catalyst; assessing initial concentrations/mixtures, temperatures, and current densities. Phenol ECH exhibited the most favourable outcome, achieving an 83.17% conversion rate and 60% Faradaic Efficiency (FE). When mixtures (BA + P, BA + G, P + G, and BA + P + G) were evaluated, revealing that BA + P yielded the highest conversion rate (64.19%) and FE (74%). This outcome suggests a potential synergistic effect between benzoic acid and phenol. Additionally, regardless of experimental parameters, BA selectivity for cyclohexane carboxylic acid (CCA) remained consistently at 100%. Density functional theory (DFT) calculations provided insight into molecular/catalyst interactions, highlighting the stability of parallel positioning the BA molecule on the cathode surface compared to perpendicular placement (-1.12 eV vs. 0.58 eV), this offers a plausible explanation for the observed high selectivity towards CCA. These findings provide a foundation for future developments in ECH of real pyrolysis oil.

Electrochemical hydrogenation (ECH) is a novel route for the upgradation of pyrolysis oil from both biomass and plastic feedstocks. Compared with conventional routes, including thermal cracking, ECH can be performed under mild conditions (<80 degrees C and 1 atm) and without the requirement of additional H-2 supply. The successful demonstration of this application can be a critical step to enabling a circular plastic economy and low-carbon fuel production. In this review we provide a critical overview of the recent advancements in understanding the variables that influence the ECH process. In addition, we debate how this technology could be optimized and applied to plastic waste pyrolysis oil, assessing concerns such as the selection of cathode material, which needs to be resilient enough to address the complex nature of bio-oil. In addition, we present ideas on how to circumvent the challenge where the commonly used water-based electrolytes are unlikely to be suitable for pyrolysis oil treatment. Finally, we discuss the possible utilization of this product and scalability of this process.

Aqueous zinc -ion batteries (AZIBs) are among those of focus in the research realm of next -generation electric energy storage, benefiting from their intrinsic safety, high volumetric capacity, and low cost. Nonetheless, the problems of lifespan and reversibility caused by dendrites, hydrogen evolution, and corrosion reactions restrict the large-scale commercialization of aqueous zinc -ion batteries. Herein, a multifunctional strategy has been explored in this research, of which the porous submicron-CaF2 layer with uniform channels is applied to the zinc anode by employing a straightforward, low-cost method. Moreover, the submicron-CaF2 coating can provide abundant submicron channels, restricting the free diffusion of Zn2 thorn and effectively preventing the growth of zinc dendrites. Additionally, a series of characterizations reveal that the Zn@CaF2 anode has a high cycle reversibility due to the marked suppression of the corrosion and hydrogen evolution reactions provided for the desolvation effects of CaF2. Consequently, the Zn@CaF2 symmetrical cell afforded a long cycling lifespan for more than 1850 h at 1 mA/cm2. Importantly, even at a high current of 8 mA/cm2, the symmetrical cell can stably maintain for 2000 cycles. As a proof of the strategy, the entire Zn@CaF2//Zn3V2O8$1.85H2O cell outperformed the full cell with bare Zn anode through superior capacity retention. (c) 2024 Elsevier Ltd. All rights reserved.

Gas turbine superalloys experience hot corrosion, driven by factors including corrosive deposit flux, temperature, gas composition, and component material. The full mechanism still needs clarification and research often focuses on laboratory work. As such, there is interest in causal discovery to confirm the significance of factors and identify potential missing causal relationships or co-dependencies between these factors. The causal discovery algorithm Fast Causal Inference (FCI) has been trialled on a small set of laboratory data, with the outputs evaluated for their significance to corrosion propagation, and compared to existing mechanistic understanding. FCI identified the salt deposition flux as the most influential corrosion variable for this limited dataset. However, HCl was the second most influential for pitting regions, compared to temperature for more uniformly corroding regions. Thus FCI generated causal links aligned with literature from a randomised corrosion dataset, while also identifying the presence of two different degradation modes in operation.

This study examines the fireside corrosion of FeCrAl, NiCr, NiCrAlY and A625 coatings applied by ‘high velocity oxy fuel’(HVOF) and exposed to simulated biomass firing conditions (gas composition CO 2 , N 2 , SO 2 and HCl). The coatings and a typical base steel alloy (T92) were exposed to simulated conditions at 600 °C for 1000 h in a laboratory scale furnace. Samples were coated with a potassium chloride deposit. Samples were then cold mounted in a low-shrinkage epoxy resin and then cross-sectioned. Corrosion was assessed by dimensional metrology comparing the coating thickness change of the samples. The cross-sections of the ‘worst’ and ‘best’ coatings were examined. Results show that all but one coating (HVOF NiCr) outperformed the T92 alloy. No coating composition or method was conclusively better. Evidence of Cr depletion as well as the formation of a sulphidation layer have been found in the exposed samples with coatings. The formation of a K 2 SO 4 layer has also been observed on all coated specimens.

Gas turbines are a key part of many countries’ power generation portfolios, but components such as blades can suffer from hot corrosion attack, which can decrease component lifetimes. Corrosion is driven by impurity levels in the fuel and air (e.g., species containing sulphur and/or alkali metals) and depends on environmental conditions (e.g., air pollution, seawater droplets), that can lead to formation of harmful species in the gas. Understanding and determining the deposition flux of such contaminants is crucial for understanding the problem. Thermodynamic simulations were used to determine types and amounts of potentially corrosive contaminants, this was followed by deposition fluxes calculations. An operating scenario, based upon an offshore platform was evaluated. The effectiveness of different filtration systems has been evaluated. The impurity levels of alkali metals, such as sodium, greatly impacts the calculated deposition flux of species linked to corrosion attack. The presence of Na 2 SO 4 , and K 2 SO 4 was found, at temperature representative of stage 2 nozzle guide vanes. Lowering sulphur input (from fuel or air) can be an efficient way to decrease deposition, attention must also be paid to lowering the amount of alkali metal entering the gas turbine, which can be lowered by the filtration systems’ correct use.

Gas turbine materials often feature precipitates containing refractory metals to enhance their mechanical strength. This can make them susceptible to alloy-induced acidic fluxing whereby refractory elements increase the acidity of salt deposits. It is not clear to what degree degradation around alloy precipitates is caused by alloy-induced hot corrosion mechanisms, or the inability to develop a protective scale where precipitates are located. The effect of alloy-induced hot corrosion was isolated from the disruption of the protective-scale formation by adding particles of molybdenum to the 80/20 (Na/K)2SO4 deposit for a ‘deposit re-coat’ style hot corrosion test. The resulting morphologies were compared to samples exposed without the addition of molybdenum. Morphology changes were investigated using scanning electron microscopy with energy-dispersive X-ray mapping. Results show a mix of sulphidation and pitting. The effects of molybdenum additions appear more severe for MarM 509 compared to PWA 1483.

To address climate change, power plants need to switch to greener fuels. One possible fuel is biomass; a carbon neutral/low carbon fuel. However biomasses' chemistries are both different from coal's and vary depending on their sources, containing unique levels of the trace elements (e.g., Cl and S) capable of altering the degradation of heat-exchangers. As such, an understanding of the effects of these variations on fireside corrosion is needed. Laboratory testing exposed alloys T91 and TP347HFG in a simulated agricultural product combustion environment at 600 degrees C (up to 1000h; 100h cycles). Three different deposits mixtures were investigated (comprised of KCl, K2SO4, Na2SO4, CaSO4 in different percentages) mimicking accelerated corrosion from different biomasses. Corrosion behaviour was found to be dependant on both alloy and deposit chemistries, with the two materials showing different responses. The deposit with lowest KCl showed lowest corrosion damage, while the highest KCl deposit showed more aggressive behaviour.

The energy sector will need to employ novel strategies to reduce greenhouse gas emissions, such as the increase of steam temperatures/pressures or the use of low carbon fuels (i.e. biomass). Both cause heat exchanger materials' degradation issues, due to the formation of more/different corrosive deposits, which requires the use of expensive nickel-based materials or coatings. This paper focuses on the behaviour of three different coatings (HVOF NiCrFeSi, laser clad FeCrAl and Laser Clad NiCrFeSi) deposited on TP347HFG, at 700 degrees C (up to 1000 h exposure). Tests were performed using the 'deposit recoat' method (KCl deposit) in simulated biomass combustion environments. Cross-sections were analysed using dimensional metrology, to determine distributions of metal loss and internal damage. Intergranular damage and pits were identified using SEM/EDX. A 'diffusion cell' behaviour was observed, which led to depletion of alloying elements from the coating and consequent increase in damage. The results suggested a severe degradation of all coatings.

To provide clarity on the poorly-understood mechanism of breakaway oxidation, corrosion of Fe9Cr1Mo steel in pressurised CO2 is quantified and modelled. The temperature range 400–640∘C, relevant to nuclear power plants, is emphasised. Attack is in the form of combined oxide scale growth and internal carburisation of the metal. Carbon activity in the metal at its surface exhibits a strong time dependence consistent with the kinetically-limited transport of carbon due to the slow Boudouard reaction. Breakaway is associated with the approach to saturation of the steel with respect to carbon. Diffusion modelling agrees well with steel carbide precipitation observations.