Key Takeaways & Executive Findings
- •• • N-MWNT-1 supported Ba-Ru catalyst achieves 7.4× higher NH3 production rate than conventional BaO-promoted Ru catalysts at 573 K and 1.0 MPa, directly reducing operational energy intensity and enabling downscaled, renewable-powered ammonia plants. • • Optimal Ba/Ru molar ratio of 0.75 balances active-site accessibility and electron enrichment; exceeding this ratio blocks Ru surfaces and collapses activity, defining a narrow compositional window for industrial catalyst formulation. • • Carbon support work function governs performance: N-MWNTs with 10–20 nm diameter exhibit the lowest work function among eleven screened carbons, maximizing long-range H+/e− pair migration and electron back-donation to N≡N antibonding orbitals. • • Feedstock purity thresholds (O2 <0.4 ppm, H2O <0.7 ppm) are mandatory to prevent catalyst poisoning; industrial implementation must incorporate stringent gas purification, adding capex but ensuring stability over extended operation.
Abstract
Ammonia synthesis remains dominated by the Haber-Bosch process, which operates at 400–500 °C and 150–300 bar, consumes 1–2% of global energy, and emits ~1.4% of global CO2. Ru-based catalysts supported on carbon and promoted with basic oxides (Ba, Cs, La) exhibit high activity under mild conditions, but conventional designs suffer from a trade-off: BaO domains block Ru active sites while attempting to donate electrons. Lee et al. (Nat Catal, 2025, 8: 248–256) resolved this by using conductive carbon to bridge isolated Ru and BaO domains, enabling long-range H+/e− pair migration. Screening eleven carbon supports, they identified N-doped multi-walled carbon nanotubes (10–20 nm diameter, N-MWNT-1) with the lowest work function as optimal. At a Ba/Ru molar ratio of 0.75, the catalyst achieved an NH3 production rate 7.4 times higher than conventional BaO-promoted Ru catalysts under 573 K and 1.0 MPa, using high-purity H2 and N2 (99.999%, O2 <0.4 ppm, H2O <0.7 ppm). This design decouples proton and electron storage, preventing BaO-induced blockage of Ru surfaces and enabling superior activity and stability. The Ba-Ru/carbon catalyst offers a transformative pathway for reducing energy consumption and integrating with electrolytic hydrogen production in industrial ammonia synthesis.
1. Introduction
Industrial ammonia synthesis remains locked into the Haber-Bosch process, operating at 400–500 °C and 150–300 bar, consuming 1–2% of global energy and emitting ~1.4% of global CO2. The reliance on fossil-derived hydrogen and extreme conditions makes integration with electrolytic H2 economically unviable without a step-change in catalyst performance. Ru-based catalysts promoted with Ba, Cs, or La oxides offer higher activity under mild conditions, but conventional designs face a persistent trade-off: BaO domains required for electron donation physically block Ru active sites, suppressing overall turnover.
Lee et al. resolve this bottleneck by separating electron and proton storage on distinct Ru and BaO domains, mediated by conductive low-work-function carbon. The carbon matrix enables long-range H+/e− pair migration, allowing BaO to capture protons without direct Ru contact while electrons accumulate in Ru/carbon domains. Screening eleven carbon materials identified N-doped multi-walled carbon nanotubes (10–20 nm) as optimal, with a Ba/Ru molar ratio of 0.75 delivering a 7.4-fold NH3 production rate increase at 573 K and 1.0 MPa. This architecture eliminates BaO-induced site blockage and provides a scalable pathway for mild-condition ammonia synthesis.
Loading authentic research manuscript (Pages 1–5)...
WANG Jiangli, CHEN Chunhong, WANG Haiyan (2025). Electron and Proton Separation on Ru-Based Catalysts Promotes Ammonia Synthesis. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3476-4
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the quantitative performance advantage of the N-MWNT-1 supported Ba-Ru catalyst over conventional BaO-promoted Ru catalysts?
Under identical mild conditions (573 K, 1.0 MPa), the N-MWNT-1 catalyst exhibits an NH3 production rate 7.4 times higher than conventional BaO-promoted Ru catalysts. This 7.4× factor directly translates to reduced reactor volume or lower operating temperature for a target output, improving capital efficiency and enabling smaller, distributed ammonia plants.
Why is the Ba/Ru molar ratio fixed at 0.75, and what failure mechanism occurs at higher loadings?
The optimal Ba/Ru molar ratio of 0.75 balances active-site accessibility and electron enrichment. Exceeding this ratio causes BaO domains to physically block Ru surfaces, reducing the number of accessible active sites and collapsing the NH3 production rate. This defines a narrow compositional window that must be tightly controlled during catalyst manufacturing.
What are the critical feedstock purity requirements, and what is the industrial cost implication?
High-purity H2 and N2 (99.999%) with O2 <0.4 ppm and H2O <0.7 ppm are mandatory. Trace O2 and H2O poison the Ru active sites and degrade the BaO promoter, leading to irreversible activity loss. Industrial implementation requires advanced gas purification units, adding capital and operating expenditure, but this is offset by the 7.4× activity gain and extended catalyst lifetime.
How does the carbon support work function influence catalytic performance, and why is N-MWNT-1 superior?
The carbon support work function governs the efficiency of long-range H+/e− pair migration. Among eleven screened carbons, N-MWNTs with 10–20 nm diameter (N-MWNT-1) exhibit the lowest work function, which maximizes electron accumulation in Ru/carbon domains and enhances back-donation into N≡N antibonding orbitals. This electronic effect directly accelerates N2 activation and boosts NH3 synthesis efficiency.
What is the stability profile of the Ba-Ru/carbon catalyst under prolonged operation, and what degradation mechanisms are anticipated?
The catalyst demonstrates superior stability compared to conventional counterparts, but long-term degradation may arise from BaO agglomeration, carbon support corrosion under reaction conditions, or trace impurity accumulation. The paper reports stability under mild conditions (573 K, 1.0 MPa) with high-purity feed; industrial deployment must monitor Ba/Ru ratio drift and carbon work function changes over thousands of hours to ensure sustained 7.4× performance advantage.
Related Chinese Research & Cross-Citations
Ammonium Vanadate Cathodes in Aqueous Zinc-Ion Batteries: Design Strategies and Research Progress
Aqueous zinc-ion batteries (AZIBs) offer a compelling combination of high safety, environmental compatibility, and abundant zinc resources, positioning them as viable candidates for grid-scale energy storage. Their practical deployment, however, is constrained by cathode materials that suffer from structural degradation, sluggish Zn2+ diffusion, and inadequate electronic conductivity. Ammonium vanadates (AVOs) have emerged as high-performance cathodes owing to their layered or tunneled frameworks, which accommodate reversible Zn2+ (de)intercalation with diffusion coefficients superior to conventional vanadium oxides. This review systematically examines recent advances in AVO cathodes for AZIBs, correlating morphological variations—including nanowires, nanobelts, and microflowers—with electrochemical characteristics. The analysis establishes structure–performance relationships that govern capacity retention, rate capability, and cycling stability. Key optimization strategies are critically assessed: defect engineering to enhance electronic conductivity and active site density, interlayer spacing modulation via pre-intercalated cations or structural water to facilitate Zn2+ transport, and composite construction with conductive carbonaceous or polymeric matrices to mitigate dissolution and improve mechanical integrity. Despite these advances, challenges persist in achieving long-term cycling stability (>10,000 cycles) and high areal mass loading (>10 mg cm-2) required for commercial viability. The review concludes by outlining future research directions, including operando characterization of degradation mechanisms and scalable synthesis routes for AVO cathodes in practical AZIB configurations.
Microenvironment-responsive therapeutic platforms: Innovations for spinal cord injury repair
Spinal cord injury (SCI) remains a formidable clinical challenge due to the complex, dynamic lesion microenvironment that impedes axonal regeneration and functional recovery. This highlight examines a microenvironment-responsive therapeutic platform integrating microneedle delivery, ferroptosis modulation, and hydrogen therapy. The platform leverages the pathological hallmarks of SCI—oxidative stress, iron dyshomeostasis, and lipid peroxidation—to achieve spatiotemporally controlled cargo release. By combining microneedle arrays for minimally invasive intraparenchymal administration with hydrogen-releasing biomaterials, the system addresses the dual bottlenecks of poor drug penetration across the blood-spinal cord barrier and insufficient neutralization of reactive oxygen species. Ferroptosis inhibition is achieved through iron chelation and glutathione peroxidase 4 (GPX4) stabilization, while hydrogen gas scavenges hydroxyl radicals and peroxynitrite. This multimodal strategy attenuates secondary injury cascades, reduces glial scar formation, and promotes neural stem cell differentiation. The work is supported by the National Natural Science Foundation of China (82574518) and the Talent Cultivation Project of Paring Academicians with Young Talents in higher education institutions in Zhejiang. The authors declare no conflict of interest. This highlight underscores the translational potential of microenvironment-responsive platforms for SCI repair, emphasizing the need for rigorous preclinical validation and scalable manufacturing.
Dual-Site Adsorption over Phosphorus-Doped Copper Oxide for Efficient CO2 Electroreduction to Ethylene
Electroreduction of CO2 to ethylene offers a promising route for renewable electricity storage, yet achieving high ethylene selectivity at industrial current densities remains challenging due to the large energy barrier for C–C coupling. Here, we report a “MOF-assisted in situ doping” strategy to introduce the oxophilic nonmetal phosphorus (P) into the copper oxide (CuO) lattice, constructing a localized Cu–P dual-site adsorption configuration for the key *OCCHO intermediate. The optimized catalyst delivers an impressive Faradaic efficiency of 64.6% for ethylene with a partial current density of 646 mA cm-2. Comprehensive structural characterizations demonstrate that P mainly occupies Cu sites, generating abundant lattice defects and oxygen vacancies. In situ synchrotron infrared spectroscopy and theoretical calculations reveal that P doping modulates the electronic structure of Cu, optimizes the binding energies of *CO and *CHO, and stabilizes *OCCHO via P–O/Cu–C dual-site adsorption, thereby significantly lowering the asymmetric C-C coupling energy barrier to 0.74 eV. This work highlights a dual-site microenvironment regulation strategy for CO2-to-ethylene electroreduction.
Hydrophilic Single-Atom Interface Unlocks Low-Potential CO Removal on Pt in PEMFCs
Proton exchange membrane fuel cells (PEMFCs) fed with reformate hydrogen suffer severe anode poisoning by trace CO, necessitating high CO electrooxidation potentials that degrade performance and durability. This work introduces a Pt@CrSA-N-C anode catalyst featuring a hydrophilic Cr single-atom interface that simultaneously weakens CO adsorption on Pt via electronic regulation and promotes water activation, thereby lowering the CO oxidation onset potential to approximately 0.13 V vs. RHE. The onset potential was determined by two independent methods: the first potential at which the background-corrected current exceeds 0 mA cm-2 during CO oxidation reaction tests in a three-electrode system, and the potential at which the forward scan current exceeds the N2 background current in CO-stripping voltammetry. The catalyst achieves a maximum power density under 100 ppm CO that surpasses reported advanced catalysts, as compiled in Table S5. Structural, spectroscopic, and electrochemical characterizations collectively establish a coherent rationale for the hydrophilic single-atom interface strategy. This approach addresses the longstanding trade-off between CO tolerance and Pt utilization, offering a viable route for low-potential CO removal in practical PEMFC anodes.
An Ionoelastomer-Based Bioinspired Wearable Electronics with Tele-Perception and Tactile Sensation for Machine Learning-Assisted Rehabilitation Management
Comprehensive assessment of rehabilitation efficiency is essential for designing appropriate training programs for better musculoskeletal functional recovery. Existing contact-receptor-dependent rehabilitation assessment systems mostly focus on assessing the restoration of muscle function by evaluating grip strength or joint flexion angle; however, parameters reflecting neuromuscular synergistic function are always overlooked. Herein, we develop an ionoelastomer-based soft artificial electroreceptor (SAER) that integrates tele-perception and tactile sensation to track the rehabilitation process, collecting signals related to approaching speed and grip strength sequentially. The SAER uses polyurethane ionoelastomer incorporated with quasi-solid conductive salt as the electric field receptor, and is integrated on a rehabilitation-training ball after assembly to establish an untethered detection device; this enables the remote capture of hand approaching parameter within a 9 cm range, followed by the quantification of grip strength when contacting and grasping. Furthermore, a data-driven assessment system is established by integrating machine learning, which accurately classifies rehabilitation efficiency into six levels; it supports for rehabilitation evaluation and training programs adjustment. Overall, the SAER-based rehabilitation management system establishes a paradigm that synergistically evaluating parameters corresponding to neuromuscular functional restoration and holds strong potential for home-based active rehabilitation for minimizing dependence on frequent clinical supervision.
Microwave-Absorbing Materials with Strong Environmental Adaptability for Corrosion Protection, Anti-Icing, and Thermal Management
Microwave-absorbing materials (MAMs) deployed on naval vessels, aerospace vehicles, and critical electronic systems face coupled electromagnetic, marine salt-spray corrosion, and extreme-temperature loads that legacy single-function absorbers cannot withstand. This review consolidates progress on three environmentally adaptive MAM classes: corrosion-protective, anti-icing, and thermal-management absorbers. The electromagnetic loss and impedance-matching fundamentals are first established, then the synergistic mechanisms, design strategies, and characterization protocols for each class are examined against representative material systems and their measured performance. The analysis identifies a shared design logic—multiscale hierarchical architecture, interfacial polarization engineering, and multifunctional phase integration—while distinguishing the divergent protection mechanisms: barrier and passivation effects for corrosion, surface-energy and latent-heat regulation for anti-icing, and phonon–electron transport decoupling for thermal management. Persistent bottlenecks include the trade-off between impedance matching and protective-layer density, the absence of standardized coupled-field test protocols, and the scarcity of long-term salt-spray and thermal-cycling durability data. Future directions are delineated: intelligent self-adaptive absorbers, multiphysics-coupled simulation frameworks, and environmentally benign multifunctional integration. The review provides a theoretical and technical basis for the design, construction, and engineering scale-up of next-generation high-performance absorbers for aerospace, electronic, and marine equipment.