NH 3 decomposition is receiving increased attention for on-site CO x -free H 2 generation. Unfortunately, the harsh reaction conditions often cause sintering of active metals. Here we report a simple method to achieve well Ni dispersion by nano-structuring the BN support with La species. The surface reaction-induced LaBO 3 nano-islands on BN support have a strong affinity for Ni atoms, which can capture and confine Ni species to yield a large population of well dispersed Ni clusters and nanoparticles. The Ni species selectively anchored on LaBO 3 islands expose more active sites and boost desorption of N 2 and H 2 , exhibiting superior activity and stability for NH 3 decomposition. In addition, it is revealed that the Ni dispersion is sensitive to the change of the support surface structure. These findings highlight the important role of support structure in determining the nature of the metal phase and provide guidance for designing catalysts with controlled catalytic structure and reactivity.
Solid oxide fuel cells (SOFCs) have gained significant attention as highly efficient energy conversion devices. Enhancing the overall performance of SOFCs relies on the development of efficient anode materials. In this study, an impregnation approach is proposed to improve the electrochemical performance of the nanocomposite Ni-GDC anode by modulating oxygen vacancies and Ni dispersion. This method successfully achieves well-dispersed Ni nanoparticles and adequate oxygen vacancies in the NiO-GDC anode, resulting in excellent TPBs and catalytic activity for SOFCs. The NiO-GDC nanocomposite exhibits a significant improvement in electrochemical activity, reaching a peak power density of 0.37 W/cm2 at 850 °C. Moreover, it demonstrates remarkable durability with a degradation rate of only 0.1%/h at −380 mA/cm2. This study provides valuable insights into the modulation of oxygen vacancies and Ni dispersion in nanocomposite Ni-GDC anodes, underscoring their potential as high-performance materials for solid oxide fuel cells. These findings contribute to the advancement of superior anode materials with improved electrochemical performance, holding tremendous potential for the development of more efficient and reliable SOFCs.
Yingying Jin,Kaihao Fan,Miao Feng,Yaoguang Wang,Hongfeng Chen,Xuesong Liu
This study investigates synergistic effects in Ni/CeO 2 catalysts for ammonia decomposition, comparing impregnation and mechanical mixing preparation methods. The impregnated catalyst achieved >90 % NH 3 conversion above 500 °C, outperforming Ni/SiO 2 and mixed counterparts. Strong interactions at the Ni-CeO 2 interface facilitated the formation of Ni-O-Ce bonds, lattice distortion, and oxygen vacancies (O v )/Ce 3+ species, enhancing Ni dispersion (34.7 nm vs. 73.1 nm) and electron transfer. Optimal NH 3 pretreatment (550 °C, 1.5 h) generated metallic Ni 0 as the primary active species, with higher Ni 0 content (XPS) and reducibility (H 2 -TPR). The novelty lies in establishing how NH 3 pretreatment dynamically assembles contiguous Ce 3+ -O v -Ni 0 triads. These sites facilitate rate-limiting N 2 desorption through localized electron donation from O v and Ce 3+ to Ni 0 , which weakens N-N bonds (NH 3 -TPD). Impregnation-derived synergy: (i) enhances Ni dispersion/reduction, (ii) promotes O v formation, and (iii) enables NH 3 -pretreatment-induced assembly of contiguous Ce 3+ -O v -Ni 0 triads that create electron-rich sites, lowering the activation barrier. This work provides a foundation for designing cost-effective catalysts via atomic-scale control of metal-support interactions.
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