共查询到20条相似文献，搜索用时 46 毫秒
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与传统纳米催化剂相比,单原子催化剂(SACs)具有独特的结构、高活性和最大程度的原子利用率等特点,使SACs成为当前催化领域的研究热点。金属有机框架(Metal-organic frameworks,MOFs)中的金属离子节点是原子分散的、配位环境明确,且结构可调,是构筑单原子催化剂的理想前驱物。近年来,大量研究报道了通过热解MOFs制得性能优异的SACs。本文介绍了通过热解MOFs构建SACs的5种主要策略,包括直接热解MOFs策略、混合金属策略、混合配体策略、空间限域策略和其他策略及由热解MOFs制得的SACs在电解水、光解水和催化储氢小分子制氢中的应用。最后,指出了未来使用MOFs衍生物构建SACs的发展方向。 相似文献
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高效析氢反应(HER)电催化剂的制备对氢能的大规模推广具有重大的意义。本文以羧甲基纤维素钠(CMC-Na)和RuCl3为原料,利用Ru离子与CMC-Na在溶液中配位制备了Ru-CMC-Na水凝胶,随后通过冷冻干燥、高温退火和酸洗制备了多孔碳负载Ru单原子和Ru纳米团簇的催化剂Ru SA+NC/C-2。催化剂RuSA+NC/C-2在酸性和碱性电解质中都具有优异的HER活性和稳定性,达到10 mA·cm-2电流密度,所需过电位分别20 mV和23 mV,经过12 h的恒电位测试其活性未见明显衰减。催化剂RuSA+NC/C-2中Ru的含量为5.52wt%,在1 mol/L KOH电解质中,过电位为0.05 V时,催化剂的质量活性是商业Pt/C的5.8倍。通过对催化剂RuSA+NC/C-2的物理表征测试发现,催化剂RuSA+NC/C-2的多孔结构和大比表面积,可以暴露更多的活性位点。Ru单原子与Ru纳米团簇结构提高了Ru原子的利用率。通过XP... 相似文献
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H2 O2及其水溶液双氧水具有强氧化性,被广泛应用于造纸、污水处理和消毒等方面.全球对H2 O2的需求量与日俱增,但传统的蒽醌法工艺复杂、成本高、效率低,氢氧直接合成法又存在很大的安全隐患.因此,电催化氧还原这种新型、绿色且安全的原位合成H2 O2方法近年来受到广泛关注.氧还原反应(ORR)是多电子反应,中间体复杂且难以测量,机理研究困难.ORR存在两种竞争的反应路径,两电子路径得到H2 O2,而四电子路径生成H2O.两电子氧还原反应(2e-ORR)的反应效率取决于催化剂的活性、选择性和稳定性.目前贵金属基催化剂(如Au、Pd)对2e-ORR显示出较好的催化性能,但昂贵、稀缺的特性限制了它们的广泛应用.当前关于电催化氧还原制备H2 O2所用催化剂的研究主要集中于三方面:(1)减少贵金属的负载.将惰性金属与活性金属相结合,得到了许多性能优异的合金材料,如Pt-Hg等.(2)发展非贵金属催化剂.碳基催化剂的缺陷、表面氧官能团(C=O、C-O等)、杂原子掺杂(N-、S-等)和过渡金属掺杂(Co、Fe等)都能够提高H2O2的选择性与催化活性.(3)发展非贵金属复合催化剂.非贵金属复合物催化剂(如MnO2/C、CoS2/C)可促进电子转移,提高H2 O2的选择性.本文系统介绍了2e-ORR的机理及测试方法,简要总结了近年来用于2e-ORR制H2 O2的贵金属基催化剂、碳基催化剂和非贵金属复合催化剂的研究进展,并在此基础上对电催化氧还原制双氧水未来的研究方向进行了展望. 相似文献
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工业界普遍采用Haber-Bosch方法在高温(400～600℃)和高压(150～300 atm, 1 atm=0.101325 MPa)条件下催化氮气裂解和加氢而合成氨气(NH3),这不仅消耗大量能源,也给环境造成很大污染。为改变这种状况,探索常温常压条件下合成NH3的全新途径已成为研究热点。电催化还原N2合成NH3是尚待探索的重点方向之一。本研究利用密度泛函理论计算,探讨了过渡金属元素(如Fe, Nb, Mo, W, Ru)和非金属元素(如B, P, S)共掺杂石墨烯作为该方向催化剂的可行性。结果表明, Mo和S(Mo/S)共掺杂石墨烯在NH3合成中具有极低的电极电势(仅为0.47 V),其速率控制步骤涉及的中间产物为*NNH。NH3合成电势比析氢反应的电势(0.51 V)低,说明N2还原制备NH3具有选择性。经从头算的分子动力学计算验证,Mo/S共掺杂石墨烯体系在室温下具有良好的热力学稳定性。电子结构分析进一步揭示,过渡金属电子... 相似文献
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孙树娟;郑南南;潘昊坤;马猛;陈俊;黄秀兵 《无机材料学报》2025,(2):113-127
为了应对能源供应紧张和环境保护的挑战,探索和开发高效催化剂成为解决能源和环境问题的关键策略。单原子催化剂(Single-atom catalysts,SACs)作为近年来新兴的催化剂类型,其独特的性质吸引了科研界的广泛关注。金属以单原子的形式负载在载体表面,实现了电子、几何结构的特殊性以及原子利用率的最大化。在能源催化、环境催化、有机催化等多个领域,SACs都表现出优异的活性、选择性和稳定性,为相关催化反应提供了强有力的支撑。更重要的是,SACs在贵金属利用方面展现出巨大的潜力。通过精确调控可以最大限度地提高贵金属的催化效率,进而降低催化剂制造成本。因此,SACs的制备方法和作用机理成为国际催化领域的研究热点。本文综述了SACs的合成策略,包括自下而上、自上而下和量子点交联/自组装,具体介绍了共沉淀法、浸渍法、原子层沉积(Atomic layer deposition, ALD)法、高温原子热迁移法和高温热解法等制备SACs的研究进展,并对SACs制备面临的挑战和未来前景进行了总结和展望。 相似文献
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基于单原子催化剂(SACs)最大的原子利用率、可调控的电子结构、高活性位点、特殊的催化反应性能以及高度稳定性等特性,研究者以N掺杂碳基材料为载体,配体单元材料为模型,将单原子催化的研究拓展到电化学生物传感材料改性领域,研究了载体、金属配位单元对SACs催化活性的影响,总结了N掺杂碳基SACs在电化学生物传感领域中的最新研究进展,提出并探讨了该多相催化剂在电化学生物传感领域的应用前景以及面临的挑战。 相似文献
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Wei Yan Ouyang Guo Qianli Xing Meijing Liao Zhuang Shi Hao Feng Yuexing Zhang Xiyou Li Yanli Chen 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(22):2300200
Currently, the rarity and high cost of platinum (Pt)-based electrocatalysts seriously limit their commercial application in fuel cells cathode. Decorating Pt with atomically dispersed metal–nitrogen sites possibly offers an effective pathway to synergy tailor their catalytic activity and stability. Here active and stable oxygen reduction reaction (ORR) electrocatalysts (Pt3Ni@Ni–N4–C) by in situ loading Pt3Ni nanocages with Pt skin on single-atom nickel–nitrogen (Ni–N4) embedded carbon supports are designed and constructed. The Pt3Ni@Ni–N4–C exhibits excellent mass activity (MA) of 1.92 A mgPt−1 and specific activity of 2.65 mA cmPt−2, together with superior durability of 10 mV decay in half-wave potential and only 2.1% loss in MA after 30 000 cycles. Theoretical calculations demonstrate that Ni–N4 sites significant redistribute of electrons and make them transfer from both the adjacent carbon and Pt atoms to the Ni–N4. The resultant electron accumulation region successfully anchored Pt3Ni, that not only improves structural stability of the Pt3Ni, but importantly makes the surface Pt more positive to weaken the adsorption of *OH to enhance ORR activity. This strategy lays the groundwork for the development of super effective and durable Pt-based ORR catalysts. 相似文献
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Shuo Wang Lei Li Kwan San Hui Feng Bin Wei Zhou Xi Fan E. Zalnezhad Jing Li Kwun Nam Hui 《Advanced Engineering Materials》2021,23(10):2100405
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Converting N2 to NH3 is an extremely valuable process but a long‐standing challenge in chemistry. The crux is the choice of catalysts, where single atomic catalysts (SAC) are always pursued as the altar of atomic catalysts. In this paper, double atomic catalysts (DAC) of TM2‐C2N with SAC of TM‐C2N (TM = Cr, Mn, Fe, Co, and Ni) for nitrogen reduction reaction (NRR) are systematically compared. Unexpectedly, TM2‐C2N are more suitable than TM‐C2N as catalysts for NRR. Moreover, the Mn2‐C2N endows the highest catalytic activity with the lowest potential of −0.23 V versus RHE, which is the best among all reported calculation results for NRR under ambient conditions. As a result, a new way to design catalysts with DAC is provided. 相似文献
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Runxi Zhu;Yanyang Qin;Tiantian Wu;Shujiang Ding;Yaqiong Su; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(8):2307315
Iron–nitrogen–carbon single atom catalyst (SAC) is regarded as one of the promising electrocatalysts for NO3− reduction reaction (NO3RR) to NH3 due to its high activity and selectivity. However, synergistic effects of topological defects and FeN4 active moiety in Fe–N–C SAC have rarely been investigated. By performing density functional theory (DFT) calculations, 13 defective graphene FeN4 with 585, 484, and 5775 topological line defects are constructed, yielding 585-68-FeN4 with optimal NO3RR catalytic activity, high selectivity, as well as robust anti-dissolution stability. The high NO3RR activity on 585-68-FeN4 is well explained by the high valence state of Fe center as well as asymmetric charge distribution on FeN4 moiety influenced by 5- and 8-member rings. This DFT work provides theoretical guidance for engineering NO3RR performance of iron–nitrogen–carbon catalysts by modulating periodic topological defects. 相似文献
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Chia‐Che Chang Sin‐Ren Li Hung‐Lung Chou Yi‐Cheng Lee Shivaraj Patil Ying‐Sheng Lin Chun‐Chih Chang Yuan Jay Chang Di‐Yan Wang 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(49)
The generation of ammonia, hydrogen production, and nitrogen purification are considered as energy intensive processes accompanied with large amounts of CO2 emission. An electrochemical method assisted by photoenergy is widely utilized for the chemical energy conversion. In this work, earth‐abundant iron pyrite (FeS2) nanocrystals grown on carbon fiber paper (FeS2/CFP) are found to be an electrochemical and photoactive catalyst for nitrogen reduction reaction under ambient temperature and pressure. The electrochemical results reveal that FeS2/CFP achieves a high Faradaic efficiency (FE) of ≈14.14% and NH3 yield rate of ≈0.096 µg min?1 at ?0.6 V versus RHE electrode in 0.25 m LiClO4. During the electrochemical catalytic reaction, the crystal structure of FeS2/CFP remains in the cubic pyrite phase, as analyzed by in situ X‐ray diffraction measurements. With near‐infrared laser irradiation (808 nm), the NH3 yield rate of the FeS2/CFP catalyst can be slightly improved to 0.1 µg min?1 with high FE of 14.57%. Furthermore, density functional theory calculations demonstrate that the N2 molecule has strong chemical adsorption energy on the iron atom of FeS2. Overall, iron pyrite‐based materials have proven to be a potential electrocatalyst with photoactive behavior for ammonia production in practical applications. 相似文献
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Shaofang Fu Chengzhou Zhu Junhua Song Mark H. Engelhard Xiaolin Li Peina Zhang Haibing Xia Dan Du Yuehe Lin 《Nano Research》2017,10(6):1888-1895
Heteroatom doping,precise composition control,and rational morphology design are efficient strategies for producing novel nanocatalysts for the oxygen reduction reaction (ORR) in fuel cells.Herein,a cost-effective approach to synthesize nitrogen-and sulfur-codoped carbon nanowire aerogels using a hard templating method is proposed.The aerogels prepared using a combination of hydrothermal treatment and carbonization exhibit good catalytic activity for the ORR in alkaline solution.At the optimal annealing temperature and mass ratio between the nitrogen and sulfur precursors,the resultant aerogels show comparable electrocatalytic activity to that of a commercial Pt/C catalyst for the ORR.Importantly,the optimized catalyst shows much better long-term stability and satisfactory tolerance for the methanol crossover effect.These codoped aerogels are expected to have potential applications in fuel cells. 相似文献
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AbstractMultilayers of gold nanoclusters (GNCs) coated with a thin Pd layer were constructed using GNCs modified with self-assembled monolayers (SAMs) of mercaptoundecanoic acid and a polyallylamine hydrochloride (PAH) multilayer assembly, which has been reported to act as a three-dimensional electrode. SAMs were removed from GNCs by electrochemical anodic decomposition and then a small amount of Pd was electrochemically deposited on the GNCs. The kinetics of the oxygen reduction reaction (ORR) on the Pd modified GNC/PAH multilayer assembly was studied using a rotating disk electrode, and a significant increase in the ORR rate was observed after Pd deposition. Electrocatalytic activities in alkaline and acidic solutions were compared both for the GNC multilayer electrode and Pd modified GNC electrode. 相似文献
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Xiong-Fei Li;Fang-Yuan Su;Li-Jing Xie;Yan-Ru Tian;Zong-Lin Yi;Jia-Yao Cheng;Cheng-Meng Chen; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(32):2310940
Graphene supported electrocatalysts have demonstrated remarkable catalytic performance for oxygen reduction reaction (ORR). However, their durability and cycling performance are greatly limited by Oswald ripening of platinum (Pt) and graphene support corrosion. Moreover, comprehensive studies on the mechanisms of catalysts degradation under 0.6–1.6 V versus RHE (Reversible Hydrogen Electrode) is still lacking. Herein, degradation mechanisms triggered by different defects on graphene supports are investigated by two cycling protocols. In the start–up/shutdown cycling (1.0–1.6 V vs. RHE), carbon oxidation reaction (COR) leads to shedding or swarm–like aggregation of Pt nanoparticles (NPs). Theoretical simulation results show that the expansion of vacancy defects promotes reaction kinetics of the decisive step in COR, reducing its reaction overpotential. While under the load cycling (0.6–1.0 V vs. RHE), oxygen containing defects lead to an elevated content of Pt in its oxidation state which intensifies Oswald ripening of Pt. The presence of vacancy defects can enhance the transfer of electrons from graphene to the Pt surface, reducing the d−band center of Pt and making it more difficult for the oxidation state of platinum to form in the cycling. This work will provide comprehensive understanding on Pt/Graphene catalysts degradation mechanisms. 相似文献
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Lei Li Xingyong Wang Haoran Guo Ge Yao Haibo Yu Ziqi Tian Baihai Li Liang Chen 《Small Methods》2019,3(11)
The MXene‐supported single transition metal systems have been reported as promising electrocatalysts for hydrogen evolution reaction (HER) and carbon dioxide reduction reaction. Herein, the potential performance of MXene‐based catalysts was explored on nitrogen reduction reaction (NRR). Density functional theory computations are carried out to screen a series of transition metal atoms confined in a vacancy of MXene nanosheet (Mo2TiC2O2). The results reveal that the Zr, Mo, Hf, Ta, W, Re, and Os supported on defective Mo2TiC2O2 layer can significantly promote the NRR process. Among them, Zr‐doped single atom catalyst (Mo2TiC2O2‐ZrSA) possesses the lowest barrier (0.15 eV) of the potential‐determining step, as well as high selectivity over HER competition. To the best of knowledge, 0.15 eV is the lowest barrier of potential‐determining step that has been reported for NRR so far. Besides, the formation energy of Mo2TiC2O2‐ZrSA is much more negative than that of the synthesized Mo2TiC2O2‐PtSA catalyst, suggesting that the experimental preparation of Mo2TiC2O2‐ZrSA is feasible. This work thus predicts an efficient electrocatalyst for the reduction of N2 to NH3 at ambient conditions. 相似文献