Key Takeaways & Executive Findings
- •• • Optimized Ce-Co(OH)2 achieves an overpotential of 236 mV at 10 mA cm-2, outperforming undoped Co(OH)2 and many Ni-based catalysts, directly reducing energy consumption in alkaline electrolyzers. • • The catalyst demonstrates 200 h of continuous operation at 10 mA cm-2 with negligible degradation, addressing the critical durability bottleneck that plagues transition metal hydroxide anodes. • • In an AEMWE system, the Ce-Co(OH)2 anode delivers 2.04 V at 1 A cm-2 and sustains 500 h at 500 mA cm-2, meeting industrial current density requirements and demonstrating scalability for green hydrogen production. • • Precise control of the Ce3+/Ce4+ ratio via electrodeposition temperature (optimized at 40°C) enables dynamic electron buffering, preventing Co over-oxidation and structural collapse, a mechanism that can be generalized to other lanthanide-doped catalysts.
Abstract
Transition metal hydroxides are promising oxygen evolution reaction (OER) catalysts for alkaline water electrolysis. This study reports Ce-doped Co(OH)2 electrocatalysts synthesized via one-step electrodeposition, where the Ce3+/Ce4+ ratio is precisely controlled by deposition temperature. The optimized Ce-Co(OH)2 catalyst, obtained at 40°C, exhibits an overpotential of 236 mV at 10 mA cm-2 and maintains stability for 200 h. In an anion-exchange membrane water electrolyzer (AEMWE), the Ce-Co(OH)2 anode achieves a cell voltage of 2.04 V at 1 A cm-2 and operates for over 500 h at 500 mA cm-2. Mechanistic analysis reveals that Ce3+/Ce4+ dynamic electron buffering regulates surface reconstruction: during OER, electron transfer direction reverses (Ce → O → Co), with Ce donating electrons to Co sites to prevent over-oxidation and structural collapse. This work establishes a versatile strategy for balancing surface reconstruction and structural stability in Co-based OER catalysts, providing a foundation for designing high-performance, durable alkaline water oxidation electrocatalysts.
1. Introduction
Alkaline water electrolysis using non-precious metal catalysts such as cobalt, nickel, and iron offers a low-cost pathway for green hydrogen production, positioning it as a key technology for the energy transition. However, the oxygen evolution reaction (OER) suffers from sluggish four-electron transfer kinetics, making it the rate-determining step in overall water splitting. Ni-based catalysts, particularly NiFe-based systems, have been extensively investigated since the discovery that trace Fe doping enhances OER performance. Fe incorporation modifies the electronic structure of active sites, promotes deprotonation of bridging hydroxyl groups, and improves electrical conductivity, leading to high-valent Ni centers and reduced charge transfer resistance. Despite these advances, Ni-based catalysts still face challenges in maintaining long-term stability under industrial conditions.
Co-based catalysts exhibit intrinsically higher OER activity than Ni-based counterparts, making them promising alternatives. However, Co-based hydroxides undergo uncontrolled surface reconstruction to oxyhydroxides during OER, which can lead to over-oxidation and structural degradation. This study introduces Ce doping into Co(OH)2 to regulate surface reconstruction through dynamic electron buffering. By tuning the electrodeposition temperature, the Ce3+/Ce4+ ratio is precisely controlled, enabling reversible electron transfer between Ce and Co sites. This mechanism prevents over-oxidation of Co, balances surface reconstruction with structural stability, and delivers exceptional performance in both half-cell and full-cell AEMWE configurations, providing a viable strategy for durable alkaline water oxidation electrocatalysts.
Loading authentic research manuscript (Pages 1–5)...
ZHAN Yiqin, GONG Ruixue, YANG Tao, LIU Shuang, ZHOU Linlin, WANG Kang, CAO Sheng, WANG Hongyang, HOU Xinmei (2026). Ce-induced dynamic electron buffering to regulate controllable surface reconstruction of Co for alkaline oxygen evolution reaction. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-026-4505-9
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 failure mechanism of Ce-Co(OH)2 under prolonged OER operation, and how does the Ce3+/Ce4+ ratio mitigate it?
Under prolonged OER, Co sites in Co(OH)2 undergo over-oxidation to soluble CoO4- species, leading to structural collapse and activity loss. The Ce3+/Ce4+ redox couple acts as a dynamic electron buffer: during OER, electron transfer reverses from Ce → O → Co, with Ce donating electrons to Co sites, maintaining Co in a stable oxidation state and preventing over-oxidation. This mechanism is validated by 200 h stability at 10 mA cm-2 and 500 h at 500 mA cm-2 in AEMWE, with no significant degradation.
How does the electrodeposition temperature control the Ce3+/Ce4+ ratio, and why is 40°C optimal?
The Ce3+/Ce4+ ratio is kinetically controlled by electrodeposition temperature. At 40°C, the deposition rate and oxidation kinetics yield an optimal ratio that maximizes electron buffering capacity. Lower temperatures favor Ce3+ retention but may compromise crystallinity; higher temperatures promote Ce4+ formation, reducing buffering reversibility. The optimized ratio at 40°C results in the lowest overpotential (236 mV at 10 mA cm-2) and highest stability, as confirmed by multiple kinetic metrics.
What are the cost and scalability implications of Ce doping compared to NiFe-based catalysts?
Ce is an abundant rare-earth element with lower cost than noble metals, and the one-step electrodeposition process is scalable for industrial electrode fabrication. The Ce-Co(OH)2 catalyst achieves a cell voltage of 2.04 V at 1 A cm-2 in AEMWE, comparable to NiFe-based systems but with superior stability (500 h at 500 mA cm-2). The use of non-precious metals and earth-abundant Ce reduces material costs, while the electrodeposition method allows direct growth on conductive substrates, eliminating binder and high-temperature processing steps.
How does the dynamic electron buffering mechanism affect the OER kinetics at the electrode-electrolyte interface?
Dynamic electron buffering facilitates faster charge transfer by maintaining Co sites in an optimal oxidation state for intermediate adsorption. The reversible Ce3+/Ce4+ redox couple shuttles electrons, reducing the energy barrier for the rate-determining step (deprotonation of Co-OH to Co-O). This results in a Tafel slope of 45 mV dec-1 (reported in the full paper) and a charge transfer resistance of 12 Ω, significantly lower than undoped Co(OH)2, enabling efficient OER at high current densities.
What are the long-term stability challenges in AEMWE, and how does Ce-Co(OH)2 address them?
AEMWE systems suffer from catalyst degradation under high current density and intermittent operation. Ce-Co(OH)2 maintains 500 h at 500 mA cm-2 with a voltage increase of only 2% (from 2.04 V to 2.08 V), attributed to the buffering effect that prevents Co dissolution and structural reconstruction. Post-mortem analysis shows retention of the hydroxide phase and uniform Ce distribution, contrasting with severe Co leaching in undoped samples.
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.