EES catalysis最新文献

Traditional studies in comprehensive multicomponent spaces driven by redundant chemical experiments may overlook important features. Herein, we introduce historical experimental data and a theoretical volcano map, coupled with thermodynamic stability, to provide insights by feature ranking based on a robust formic acid oxidation reaction (FOR) database. Results indicate that the PdCuNi alloy catalyst screened by density functional theory (DFT) calculations and machine learning (ML) is a promising candidate for FOR. Electron-deficient surface Ni atoms promote the reduction of the thermodynamic energy barrier of FOR. A PdCuNi medium entropy alloy aerogel (PdCuNi AA) was successfully synthesized through a simple one-pot NaBH₄-reduction synthesis strategy. The obtained catalyst exhibits a mass activity of 2.7 A mg⁻¹, surpassing those of PdCu, PdNi and commercial Pd/C by approximately 2.1-, 2.7- and 6.9-fold, respectively. Moreover, PdCuNi AA achieves an impressive power density of around 153 mW cm⁻² with 0.5 mg cm⁻² loading in the anode of direct formic acid fuel cells. Combining cutting-edge methods to drive innovative catalyst design will play a key role in advancing the development of fuel cells.

Developing economical and environmentally friendly carbonylation synthetic methods is an important and challenging goal. Exploring the application of non-precious metal catalysts in synthetic chemistry has proven to be an ideal choice due to their abundancy, low cost, and low toxicity. In recent years, as copper is one of the cheaper metals, copper catalysts have been widely used in the field of carbonylative transformations. In this review, case-by-case reaction modes and mechanisms are summarized and discussed, along with a personal perspective. Various organocopper intermediates were produced from the single-electron reduction of alkyl halides, capturing radicals from the oxidation of carbon-hydrogen bonds, transmetalation, and active copper species addition to unsaturated bonds (active Cu–H, Cu–Bpin or Cu–Si intermediate), and then, different organocopper intermediates can result from nucleophilic quenching, electrophilic quenching, transmetalation, isomerization to carbene, etc.

Hydrogen is a promising clean and renewable energy source; however, its efficient storage is one of the key challenges in establishing the sustainable hydrogen economy. The light main group metals and their tetrahydroborates and tetrahydroaluminates show great potential for high hydrogen storage capacity close to ambient conditions; however, their high hydrogenation and dehydrogenation temperatures, sluggish kinetics, and limited reversibility have always been an obstacle for practical applications. Large efforts have been devoted to modifying the thermodynamic and kinetic properties of these systems, and reviewing these efforts and highlighting future directions are the aims of the present review. Based on recent research, the application of multicomponent systems utilizing multiple modification methods, such as catalysis, nanoconfinement, alloying, and structure engineering, is essential for enhancing the storage conditions. The synergistic effect of multiple catalysts is now a key requirement to address various steps of the overall process, including forming/breaking the H–H and metal–H bonds, transporting hydrogen and heat, and suppressing the formation of side products. Compared to pristine systems, tremendous improvement has been achieved. Catalysed AlH₃ decomposition can now operate as a one-way hydrogen source below 100 °C and the Mg/MgH₂ hydrogen storage system exhibits good cyclic performance at elevated temperatures. Metal hydrides, tetrahydroborates, tetrahydroaluminates, and their composite systems face challenges in achieving close to ambient operating conditions and cyclic stability. As the demand for improved hydrogen energy storage is expected to grow, further research for the enhancement of these systems will continue to advance the state of hydrogen storage technology.

Heterogeneous molecular Fe–N–C catalysts hold promise for the oxygen reduction reaction (ORR), but their stability in acidic media remains a bottleneck. Here, we report the synthesis of a self-renewal Fe–N–C catalyst by uniformly polymerizing an iron polyphthalocyanine (FePPc) shell around carbon nanotubes (CNTs) via a microwave-assisted method. This FePPc/CNT catalyst achieves a much higher Fe mass loading (2.92 wt%) compared to directly depositing iron phthalocyanine (FePc) molecules on CNTs (FePc/CNT, 0.80 wt%) while maintaining a similar density of exposed Fe–N₄ sites to electrolytes. FePPc/CNT exhibits superior ORR activity in 0.1 M HClO₄ electrolyte with a half-wave potential (E_1/2) of 0.74 V (vs. reversible hydrogen electrode), a low Tafel slope of 51 mV dec⁻¹, and a high turnover frequency (TOF) of 0.98 site⁻¹ s⁻¹. Density functional theory (DFT) calculations attribute this enhanced activity to strong FePPc–CNT interactions that facilitate efficient electron transfer and favorable reaction energetics. Critically, FePPc/CNT demonstrates enhanced stability in the acidic electrolyte, retaining ∼80% of its initial current density after 24 h of the chronoamperometric test, outperforming FePc/CNT (42% after 5 h) and physically mixed FePPc and CNTs (49% after 24 h). Quantitative analysis reveals a unique self-renewal mechanism involving layer-by-layer shedding of FePPc, which exposes fresh active sites to sustain catalytic activity. At the same time, detached FePPc fragments sediment on CNTs. Furthermore, leached Fe ions migrate onto CNTs and aggregate into FeO_x nanoclusters, eventually leading to irreversible deactivation. These findings provide new insights for designing durable Fe–N–C catalysts for various reactions.

The practical deployment of an anion exchange membrane water electrolyzer (AEMWE) relies on the exploration of active and durable electrocatalysts towards the sluggish oxygen evolution reaction (OER). Although amorphous NiFe-based catalysts (a-NiFeO_xH_y) emerge as the competitive candidate due to impressive intrinsic OER activity, their unique defective structure renders the metal sites more susceptible to over-oxidation and dissolution, leading to poor stability. To address this challenge, we incorporate borate groups (BO₃³⁻) into the a-NiFeO_xH_y lattice by occupying the oxygen vacancy sites. The bridged borates not only maintain the structural stability via filling the oxygen vacancies, but also assist electron transfer from Ni to Fe to suppress Fe ion dissolution, thereby enhancing the catalytic stability of a-NiFeO_xH_y. Moreover, the tailored electronic structure of Ni favors electrochemical reconstruction to high-valence Ni active species and optimizes adsorption of oxygen intermediates towards superior OER activity. Therefore, a-B-NiFeO_xH_y integrated into the AEMWE can deliver a noteworthy current density of 4.75 A cm⁻² at a voltage of 2.0 V and maintain stable operation at 0.5 A cm⁻² for 3000 hours. This study not only affords a promising electrocatalyst for the AEMWE, but also paves a new avenue to break the activity-stability trade-off of amorphous materials for the OER.

Electrochemical nitrate reduction (ENR) is an appealing method for remediating nitrate contamination in wastewater and producing ammonia using renewable electricity. However, a mechanistic understanding of coupled mass transfer and electrocatalysis at the electrode–electrolyte interface, which dictates ENR efficiency, is limited. In this study, we develop an experimentally-validated multiphysics model of the Stern, diffuse, and diffusion layers near the surface of a polycrystalline titanium catalyst to investigate the effect of the electric double layer on ENR. The developed model couples the generalized-modified-Nernst–Planck equation with Frumkin–Butler–Volmer kinetics and numerical optimization to quantify the effect of applied potential and bulk electrolyte concentration on the ammonia formation rate. Our results reveal how dynamic driving forces at the polarized interface give rise to experimentally observed trends in ENR. Guided by this insight, we show that a more negative potential-of-zero-charge increases the limiting current density for ammonia synthesis by enabling faster migration of nitrate towards the cathode surface. The results motivate the development of multi-scale models that link transport phenomena with molecular-scale modelling to design and tailor interfaces for efficient ENR.

Water electrolysis hydrogen production technology directly generates high-purity hydrogen through electrochemical water splitting, serving as a key technology for achieving zero-carbon emission hydrogen production. Alkaline water electrolysis demonstrates marked advantages in efficiency and rapidly developing anode catalysts in an alkaline medium. Nevertheless, the sluggish kinetics of the hydrogen evolution reaction (HER) at the cathode in an alkaline environment constitute a fundamental bottleneck that restricts the extensive application of this technology. Platinum, serving as the benchmark catalyst for the HER, is limited in its large-scale development due to its scarcity and high cost. In comparison, carbon-supported platinum-based catalysts exhibit exceptional HER catalytic activity and stability, driven by their unique electronic architecture and the synergistic effect with the support. In this review, we comprehensively examine the latest progress of carbon-supported platinum-based materials for the alkaline HER, summarize the factors contributing to the slow kinetics of the HER in an alkaline environment, and then focus on the strategies for modifying the carbon substrate and synthesizing carbon-supported platinum-based nanomaterials. Finally, the review critically evaluates existing challenges and proposes targeted research directions to advance Pt-based electrocatalysts for practical alkaline hydrogen evolution systems.

The electrosynthesis of adipic acid through the cyclohexanol oxidation reaction (COR) can address the pollution issues associated with the traditional process. However, the complexity of the electrooxidation process and unclear dehydrogenation and oxidation mechanisms limit its application. Herein, we report oxygen vacancy (V_O) modification on NiCo hydroxides for the selective electrosynthesis of adipic acid. In situ IR and DFT calculations revealed significantly enhanced adsorption capacity and an optimized process for the co-adsorption of OH⁻ and organic compounds. The V_O promotes the conversion of ketone intermediates into glycol with the addition of H₂O while inhibiting the formation of ketone alcohols. In situ synchrotron radiation and Raman analyses reveal the reversible remodeling processes of Ni²⁺–OH and Ni³⁺–OOH during the COR. Consequently, V_O-NiCo demonstrated excellent COR performance (1.32 V vs. RHE onset potential) with conversion, adipic acid selectivity, and faradaic efficiency values of 98.4%, 95.6%, and 95.2%, respectively. The system generates 8.2 times more hydrogen compared with pure water splitting at the cathode. This integrated electrocatalytic system shows potential for large-scale production of H₂ and adipic acid, offering new insights for designing advanced electrocatalysts for cost-effective and sustainable energy conversion.

The reverse water–gas shift (RWGS) reaction has been recognized as a promising strategy for CO₂ valorization. However, it faces limitations due to low activity and poor CO selectivity at low temperatures. In this study, we report that plasma can effectively promote the low-temperature RWGS reaction over Ni–In intermetallic catalysts. The formation of the Ni–In intermetallic phases completely suppresses CH₄ formation and achieves 100% CO selectivity. Through in situ transmission infrared spectroscopy (TIR) and in situ X-ray absorption fine-structure (XAFS) analysis, we monitored the changes occurring on the catalyst surface during the plasma reaction. The interaction between redox-active sites present in the Ni–In intermetallic catalysts and plasma-activated species lowers the activation energy, thereby facilitating the RWGS reaction at low temperatures. This study offers fundamental insights into how plasma-activated species enhance catalysis and the underlying mechanisms of low-temperature activation in plasma catalysis.

Plasma catalysis offers a promising alternative to current ammonia production processes, due to the combination of high selectivity of heterogenous catalysis and efficient activation of nitrogen in the plasma. However, the theoretical understanding of how various plasma processes contribute to efficiency improvements remains limited. The pioneering work of Metha et al. (Nat. Catal., 2018, 1, 269) extended the standard formulation of transition state theory by making it vibrational state-specific through the use of the Fridman–Macheret α model. The resulting microkinetic model accounted for vibrational contributions under the non-equilibrium conditions of a plasma reactor. In this work, we critically examine the prototypical chemical process of activated N₂ reactivity on ruthenium through explicit rate coefficient calculations using state-of-the-art molecular dynamics, based on a potential energy surface previously validated against molecular beam experiments. Our findings reveal that vibrational activation is significantly more effective in promoting surface reactivity than predicted by the Fridman–Macheret α model, which fails to capture the full complexity of state-specific contributions. Furthermore, our calculations indicate that vibrational activation is also the primary driver of highly activated thermal catalytic reactions. These results provide a valuable benchmark to guide the development of future state-specific microkinetic models for heterogeneous and plasma catalysis.