Faraday Discussions最新文献

The electrification of chemical manufacturing requires electrochemical processes that are not only selective, but also simple in composition, energy-efficient, and scalable. In organic electrosynthesis, however, the use of supporting electrolytes often complicates product isolation and reduces process practicality. Herein, we demonstrate the supporting-electrolyte-free electrochemical synthesis of hydroquinone (HQ) from benzoquinone (BQ) in solid polymer electrolyte (SPE) electrolyzers coupled with water oxidation. In a proton exchange membrane (PEM) electrolyzer, BQ was efficiently reduced to HQ without any added supporting electrolyte, and Ketjenblack outperformed carbon-supported metal catalysts as the cathode material. This result indicates that outer-sphere electron transfer at the carbon surface is sufficient for quinone reduction, whereas supported metals instead may promote competing hydrogen evolution. The PEM electrolyzer also enabled substantially lower-voltage electrolysis than a conventional batch-type divided cell, and gram-scale synthesis of HQ was achieved in 97% gravimetric yield with >99% purity by simply removing solvent after the electrolysis. In addition, the operating current density could be tuned according to the desired balance between productivity and energy efficiency. By contrast, an anion exchange membrane (AEM) electrolyzer showed markedly different behaviour: less hindered benzoquinones underwent side reactions under the basic interfacial environment, causing membrane fouling and cell-voltage increase, whereas a sterically protected quinone was reduced smoothly. These results demonstrate that SPE electrolyzers provide a practical platform for supporting-electrolyte-free organic electrosynthesis and, more importantly, that the membrane-defined reaction environment is a decisive factor governing substrate compatibility.

Time-resolved X-ray absorption spectroscopy (TR-XAS) at X-ray free-electron lasers enables element-specific probing of ultrafast dynamics, but soft X-ray measurements are often limited by low fluorescence yield, strong shot-to-shot fluctuations, and radiation damage in organic thin films. Here, we present a unified framework combining analytical signal-to-noise ratio (SNR) modelling with regression-based analysis for fluorescence-detected soft X-ray absorption spectroscopy. The SNR model predicts fundamentally different optimal conditions for static and transient measurements, with transient experiments requiring thin films (∼80-100 nm) and substantially higher photon counts. We apply this framework to shot-resolved total fluorescence yield XAS measurements of the non-fullerene acceptor Y6 at the nitrogen K-edge using a high-repetition-rate XFEL source, comparing low-dose and intermediate-dose regimes relevant to transient and static measurements, respectively. A calibration-based flux reconstruction systematically improves the fluorescence-flux correlation, while the dominant improvement arises from reformulating XAS extraction as a shot-resolved regression problem. Compared to the conventional ratio-of-means estimator, the regression-based estimator reduces the run-to-run spectral variability by up to a factor of ∼4.4 in the low-dose regime most relevant for transient measurements. Residual-based outlier rejection was found to systematically degrade reproducibility, indicating that the tails of the shot distribution primarily reflect intrinsic XFEL fluctuations rather than detector artefacts. These results demonstrate that reliable soft X-ray TR-XAS requires the joint optimisation of experimental design and statistical inference, providing a practical framework for extracting robust observables from low-signal XFEL measurements in dose-limited regimes.

Solid Oxide Cell (SOC) technology is increasingly establishing itself globally as a mature technology for both power generation and green hydrogen production. In particular, Ceres' metal supported SOC Endura platform, which combines robustness, efficiency and low manufacturing cost, has been licensed by multiple companies globally to manufacture hundreds of MW per year with factories in operation or under construction. At the core of Ceres' technology is a highly differentiated metal-supported SOC based predominantly on ceria-derived ceramics, which in turn enable low (<650 °C) temperature operation. A key novel area of research and development for Ceres' SOC technology is co-electrolysis. Co-electrolysis, which is the electrochemical and catalytic activation of steam and carbon dioxide, allows the formation of base chemistries from an electrochemical cell. Ceres' SOC operating conditions allow co-electrolysis to proceed with the formation of either methane or syngas. This combined process allows renewable methane and syngas to be produced. Experiments with the SOC have shown that methane is formed at lower temperatures with high steam utilisation, whereas syngas is produced under higher temperatures with low steam utilisation. The paper will discuss the progress of solid oxide technology for all these applications related to sustainable electrofuels and discuss co-electrolysis and the boundary conditions which impact selectivity and yield for both methane and syngas formation whilst maintaining SOC thermoneutral operation and the challenges for the use of electrochemical cells for primary molecule formation.

Developing novel molecular catalysts for electrochemical CO₂ reduction can play an important role for the development of highly selective transformations towards valuable compounds such as CO, HCOOH and CH₃OH. Iron porphyrins have shown promising activity in CO₂-to-CO electroreduction, as the porphyrin macrocycle structure can be finely modulated to tune CO₂ activation. Both charged and hydrogen-bonding substituents on the porphyrin macrocycle were previously shown to enhance catalytic reduction. In the current study, we probe if halogen bonding (XB) could be leveraged as a new mode of CO₂ activation in iron porphyrin electrochemistry. A range of ortho-substituted iodo and bromo iron porphyrins were synthesized and their electrochemical behaviour analyzed in detail. While all iodo-compounds and one bromo-compound led to C-halogen bond cleavage at the potentials necessary for CO₂ reduction, all other bromo-complexes were shown to be highly selective for CO₂-to-CO electroreduction. Cyclic voltammetry and DFT calculations, combined with a detailed mechanistic analysis, enabled deconvolution of through-bond and through-space effects in these novel XB-capable iron porphyrins and it was found that σ-hole modulation mitigates unfavourable through-space repulsion at the reduced Fe(0) state.

Ammonia decomposition (cracking) is a crucial step in the ammonia value chain for its use as an H₂ carrier. Thermocatalytic ammonia decomposition is the main route under investigation, with electrocatalysis as an emerging direction. However, due to the drastic differences in operating conditions, comparing these routes and the third alternative, membrane-assisted thermocatalytic ammonia decomposition, to determine which offers a better prospect is challenging. Here, we have compared Pt(100)/C, Pt-Ru/C, and Ru/C nanoparticles supported on conductive carbon as benchmark materials to facilitate direct comparison and have also developed a method to enable it. It was found that the thermocatalytic route is preferable to the electrocatalytic one. Although the latter still yields inferior overall productivity, performance is comparable under some conditions, indicating the direction toward superior process intensification through electrocatalysis. Notably, integrating an H₂-permeable membrane into the thermocatalytic route allows a substantial reduction in operating temperature while preserving catalytic performance. The Ru catalyst performs better than the others in both thermo- and electrocatalysis, but for different mechanistic reasons. In particular, the behavior in electrocatalysis is determined by its superior ability to promote both anodic water electrolysis and ammonia electrolysis. However, Ru also has other limitations to consider when used as the preferred metal choice.

International shipping faces a critical decarbonisation challenge, with lifecycle greenhouse gas (GHG) emissions continuing to rise despite efficiency improvements and projected to grow substantially without intervention. This paper evaluates the viability of alternative maritime fuel pathways through a systematic well-to-wake (WtW) life cycle assessment (LCA), examining ammonia, methanol, hydrogen, and power-to-liquid fuels across a range of production routes. Results reveal substantial intra-pathway variability, with only fuels derived from low-carbon electricity and rigorously controlled carbon inputs consistently achieving intensities compatible with long-term decarbonisation targets. The analysis identifies a structural misalignment between empirical evidence and existing policy frameworks, which continue to rely in part on tank-to-wake (TtW) accounting. This misalignment risks incentivising fuel pathways that are formally compliant but environmentally ineffective, leading to inefficient capital allocation and potential technological lock-in. The paper argues for the adoption of quantitative WtW GHG intensity thresholds as the foundation of maritime fuel regulation, replacing reliance on categorical "colour" taxonomies. Beyond lifecycle emissions, the paper introduces a novel analysis of the geographical concentration of e-fuel production. Emerging supply chains are increasingly clustered in regions with low-cost renewable resources, creating a divergence between the locations of fuel production and regulatory demand, particularly in Europe and the UK. This raises critical concerns regarding lifecycle emissions from transport, the externalisation of industrial value, and the potential reconfiguration of global energy dependencies. The findings demonstrate that maritime decarbonisation is a systems-level challenge spanning emissions accounting, industrial strategy, and energy security. Effective policy must therefore integrate robust WtW methodologies with interventions that address supply chain geography and support the development of domestic e-fuel production capacity.

The electrochemical carbon dioxide reduction reaction (eCO₂RR) on boron-doped diamond (BDD) electrodes predominantly yields formic acid (HCOOH) as the primary product. Redirecting the reaction pathway toward highly valuable carbon monoxide (CO) remains a significant challenge due to the chemical inertness of the BDD surface. Herein, we present an interfacial engineering strategy to tune the product selectivity from HCOOH to CO on BDD electrodes. First, functionalisation of the BDD surface with nitrogen-containing molecules such as aniline and pyrazole effectively captured CO₂, successfully directing the reaction pathway toward CO, and established molecular modification as a proof of concept for redirecting selectivity. Second, utilising an aqueous KClO₄ electrolyte dynamically facilitated CO production by minimising specific anion adsorption, providing a considerably more facile and practical route to the same selectivity switch. Through systematic optimisation of the eCO₂RR conditions in 0.1 M KClO₄, we achieved a maximum faradaic efficiency for CO production (FE_CO) of 72% at an applied potential of -1.9 V (vs. Ag/AgCl; -1.46 V vs. RHE), an electrolyte flow rate of 500 mL min^-1, and an operating temperature of 5 °C. Electrochemical analyses revealed that increasing the flow rate enhanced the CO₂ supply by significantly reducing the diffusion layer thickness. Moreover, decreasing the temperature not only increased CO₂ solubility but also selectively suppressed the competing hydrogen evolution reaction (HER). Temperature-dependent linear sweep voltammetry experiments further revealed that this suppression is driven primarily by a negative shift of the HER onset potential rather than by any appreciable shift of the CO₂ reduction onset. These findings provide fundamental insights into the reaction mechanisms on inert sp³-carbon surfaces and demonstrate that interfacial engineering is an effective strategy for developing selective CO₂ conversion systems on BDD, although practical implementation will require further advances in electrode fabrication, operating conditions, and energy efficiency.

In this work, we approach the simulation of the light-induced ultrafast dynamics of furan from a new angle. We deeply investigate the impact of the explicit inclusion of the incident pulse and the description of protic and aprotic solvents on the photorelaxation. Upon excitation, furan is driven back to its electronic ground state via two deactivation channels: one characterized by ring-puckering of the oxygen and one by ring opening via breaking of the carbon-oxygen bond. We found that explicitly including an 11 fs pulse in the simulation has a slight accelerating effect on the population dynamics; in addition, we could see an increase in the coherent motion of the puckering mode of furan. Interestingly, both solvents facilitate the ring opening, but it is more enhanced in protic methanol due to hydrogen-bonding of the solvent stabilizing the ring-open molecule. Overall, the study validates the general robustness of the routine approximation of simulating photodynamics in the gas phase using the sudden excitation approximation, but it also highlights differences that form the basis for future improvements of extending nonadiabatic dynamics simulations to an improved description of solvent and field effects.

A balanced and efficient description of excited states is essential for accurately capturing ultrafast relaxation processes. In this context, the recently developed mixed-reference spin-flip time-dependent density functional theory (MRSF-TDDFT) has demonstrated strong performance. However, its broader applicability to realistic systems requires seamless integration with multiscale simulation frameworks. In this work, we present a modular strategy that integrates MRSF-TDDFT with nonadiabatic molecular dynamics (NAMD) and electrostatic potential fitting (ESPF)-based QM/MM embedding methodologies, in which OpenQP (Open Quantum Platform) serves as a modular electronic-structure backend. To further enhance usability and interoperability, we introduce the Open Simulation Manager (OpenSM), a high-level orchestration framework that unifies QM, QM/MM, and NAMD workflows through a consistent and minimal input interface. The resulting OpenQP-OpenSM provides a flexible and extensible platform for multiscale excited-state simulations, enabling rapid integration of advanced electronic-structure methods and fostering collaborative development.

Chemical reactivity is governed by the time-dependent redistribution of valence electron density, yet ultrafast diffractive imaging probes are typically dominated by scattering from the atoms and/or core electrons and therefore primarily report nuclear motion. Building on recent hard X-ray time-resolved scattering measurements of photoexcited deuterated ammonia, we extend ultrafast X-ray scattering off the evolving valence electron density into a real-space framework by retrieving the time-dependent electron pair density (PD). Using scattering difference signals, we reconstruct transient real-space ΔPDs that directly recover: (i) the prompt redistribution of valence electron density following excitation into a diffuse Rydberg orbital, (ii) the subsequent localization of the electron density on the fragments following N-D bond fission, and (iii) distinct electronic-structure fingerprints of ballistic dissociation channels. These ΔPDs provide an intuitive, chemically interpretable measure of bond breaking and rearrangement by tracking the emergence, displacement, and loss of electron density between atomic centers while retaining femtosecond time resolution. Comparison with ab initio simulations guides the interpretation of the recovered ΔPDs and supports the inferred pathway assignments.