Xin Xiao  Hao Zhang  Ying Xiong  Feng Liang  Ying-Wei Yang 《Advanced functional materials》2021,31(42):2105562

Utilizing supramolecular synthetic macrocycles with distinct porous structures and abundant functional groups as a precursor for metal-doped carbon electrocatalysts can endow the resulting materials with great potential in electrocatalysis. Herein, iridium-doped electrocatalysts (CBC-Ir), using a synthetic macrocycle named cucurbit[6]uril as the carbon source precursor, are designed and prepared. Interestingly, owing to the numerous N-containing backbone and unique porous structure from cucurbit[6]uril self-assembly, the newly designed catalysts CBC-Ir possess abundant N-doped and mesoporous structures without the need of additional N sources and templates. The catalysts exhibit superior catalytic performance toward the hydrogen evolution reaction with high Faradaic efficiency (91.5% and 92.7%), superior turnover frequency (2.1 and 0.69 H₂ s⁻¹) at the 50 mV overpotential, and only 17 and 33 mV overpotentials in acidic and alkaline conditions reaching the current density of 10 mA cm⁻², better than the commercial Pt/C (28 and 43 mV). This work not only expands the application of supramolecular macrocycles in the water splitting field but also provides a new approach for preparing robust electrocatalysts.  相似文献   

    

Xiaohong Wang;DongXu Li;Juguo Dai;Qian Xue;Chunying Yang;Long Xia;Xueqiang Qi;Bingtao Bao;Siyu Yang;Yiting Xu;Conghui Yuan;Weiang Luo;Andreu Cabot;Lizong Dai; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(22):2309176

Metal nanoclusters providing maximized atomic surface exposure offer outstanding hydrogen evolution activities but their stability is compromised as they are prone to grow and agglomerate. Herein, a possibility of blocking metal ion diffusion at the core of cluster growth and aggregation to produce highly active Ru nanoclusters supported on an N, S co-doped carbon matrix (Ru/NSC) is demonstrated. To stabilize the nanocluster dispersion, Ru species are initially coordinated through multiple Ru─N bonds with N-rich 4′-(4-aminophenyl)-2,2:6′,2′′-terpyridine (TPY-NH2) ligands that are subsequently polymerized using a Schiff base. After the pyrolysis of the hybrid composite, highly dispersed ultrafine Ru nanoclusters with an average size of 1.55 nm are obtained. The optimized Ru/NSC displays minimal overpotentials and high turnover frequencies, as well as robust durability both in alkaline and acidic electrolytes. Besides, outstanding mass activities of 3.85 A mg−1Ru at 50 mV, i.e., 16 fold higher than 20 wt.% Pt/C are reached. Density functional theory calculations rationalize the outstanding performance by revealing that the low d-band center of Ru/NSC allows the desorption of *H intermediates, thereby enhancing the alkaline HER activity. Overall, this work provides a feasible approach to engineering cost-effective and robust electrocatalysts based on carbon-supported transition metal nanoclusters for future energy technologies.  相似文献   

    

Judith Zander  Julia Petra Wölfel  Morten Weiss  Yiqun Jiang  Ningyan Cheng  Siyuan Zhang  Roland Marschall 《Advanced functional materials》2024,34(4):2310179

High-entropy oxides are a material class that is currently receiving rapidly increasing attention due to the large variety in composition and the adjustable properties. Cooperative effects between different metal cations in the crystal structure in addition to entropic phase stabilization have proven beneficial for electrocatalytic applications. Most synthesis methods, however, require high synthesis temperatures and long times, and additionally only yield selected samples in good phase-purity. Furthermore, toxic or scarce elements are often present in large amounts. Herein, a non-aqueous microwave-assisted solvothermal synthesis is presented as a fast and low-temperature alternative for the fabrication of a wide range of earth-abundant ferrites (AFe₂O₄). Directly crystalline, phase-pure spinel ferrites of various compositions ranging from one to seven different A-ions are successfully obtained after only 30 min at 225 °C. A detailed characterization of their properties in relation to their composition is performed, and they are also employed for the alkaline oxygen evolution reaction. A partial replacement of Fe by Co moreover shows the high versatility of the synthesis that also allows for the simultaneous variation of the B-ion.  相似文献   

    

Zhenhua Tao  Hongyu Zhao  Ning Lv  Xu Luo  Jun Yu  Xin Tan  Shichun Mu 《Advanced functional materials》2024,34(19):2312987

Active and durable catalysts for hydrogen evolution reaction (HER) are of great significance for developing renewable hydrogen energy. Herein, crystalline/amorphous-Ru/VO_x (c/a-Ru/VO_x) heterogeneous catalysts are conceived, in which the amorphous VO_x exposes more active sites and enhances charge transport compared with the counterpart with a crystal phase structure, strengthening the electronic interaction between metal-support. As expected, c/a-Ru/VO_x-500 with heat treatment at 500 °C exhibits excellent HER performance under alkaline conditions, with an overpotential of only 33 mV at 10 mA cm⁻² and small Tafel slope (27 mV dec⁻¹), superior to commercial platinum/carbon (Pt/C) catalysts. Particularly, its mass activity (0.335 A mg_Ru⁻¹) is 1.5 times greater than that of Pt/C (0.224 A mg_Pt⁻¹) at an overpotential of 50 mV. Also, it shows good industrial application prospects through tests under high temperature, high alkalinity, and large current conditions. Theoretical calculations unveil that there exists a charge redistribution at c/a-Ru/VO_x heterointerfaces, which makes the surface of Ru takes on an electron-deficient state, resulting in optimization of adsorption and desorption for different reaction intermediates. This optimized behavior effectively reduces the thermodynamic energy barrier, allowing the catalyst with greatly enhanced HER performance. The exploration provides a promising strategy for designing efficient and durable catalysts for HER.  相似文献   

    

《Advanced Materials Interfaces》2018,5(7)

A new strategy to in situ immobilize iron (Fe) single clusters on N‐doped porous carbon under the confinement effect of N‐coordination supplied by porphyrins is demonstrated. During the pyrolysis reaction, the strong chelated interaction between Fe and N atoms serves as the pivotal role for achieving Fe single clusters via inhibiting the superabundant aggregation of Fe atoms. Compared to the Fe‐based nanoparticles and commercial Pt‐C, the synthesized single Fe cluster catalyst (C/TP‐Fe700) owns a superior catalytic performance in alkaline medium, which is confirmed by the more positive half‐wave potential (0.865 V, 28 mV higher than Pt‐C), high mass activity (0.60 A mg⁻¹_Fe, 10 times larger than Pt‐C), the excellent durability and remarkable methanol tolerance. Additionally, it likewise presents satisfactory oxygen reduction reaction activity in acidic medium compared with Pt‐C. This single metal cluster (metal cluster with subnanometer) catalyst with trace‐metal contents displays double advantages from metal and metal‐free oxygen reduction catalysts, such as high activity, ultralight mass, and environmental friendliness. Insight into this successful paradigm can provide a novel concept for constructing and understanding oxygen reduction catalysts at an approximate atomic scale.  相似文献   

    

《Advanced Materials Interfaces》2018,5(16)

A plasma‐enhanced atomic layer deposition (ALD) process is presented, capable of producing thin conformal films of nickel(II) oxide (NiO) on various substrates. Nickelocene (NiCp₂) is used as an inexpensive metal precursor with oxygen plasma as the oxidant. The film growth rate saturates with both nickel precursor and plasma exposure. An ALD window is observed between 225 and 275 °C. Linear growth is achieved at 250 °C with a growth rate of 0.042 nm per cycle. The thickness is highly uniform and the surface roughness is below 1 nm rms for 52 nm thick films on Si(100). Substrates with aspect ratios up to 1:10 can be processed. As‐deposited, the films consist of polycrystalline, cubic NiO, and are transparent over the entire visible range with an optical bandgap of 3.7 eV. The films consist of stoichiometric NiO and contain ≈1% of carbon impurities. Two promising applications of these films are showcased in renewable energy conversion and storage devices: The films are pinhole‐free and exhibit excellent electron blocking capabilities, making them potential hole‐selective contact layers in solar cells. Also, high electrocatalytic activity of ultrathin NiO films is demonstrated for the alkaline oxygen evolution reaction, especially in electrolytes containing Fe³⁺.  相似文献   

    

《Advanced Materials Interfaces》2018,5(15)

Lithium–sulfur batteries (LSBs) have been regarded as the supreme feasible future generation energy storage system for high‐energy applications due to the exceptional‐specific energy density of 2600 Wh kg⁻¹ and theoretical‐specific capacity of 1675 mAh g⁻¹. Nevertheless, some key challenges which are linked with polysulfide shuttling and sluggish kinetics of polysulfide conversion are the main obstacles in the high electrochemical performance of LSBs. Here, a molybdenum trioxide (MoO₃) nanobelt catalytic layer is fabricated on the separator to solve these issues. The MoO₃ layer shows strong chemical interaction with polysulfides by successfully blocking the polysulfides on the separator from shuttling and significantly accelerates the redox reaction of polysulfide conversion. Furthermore, the randomly arranged layers of MoO₃ nanobelts possess enough porous networks that provide effective space for electrolyte infiltration and facile pathway for fast ion transportation. The resultant LSBs exhibit a very high initial capacity of 1377 mAh g⁻¹. After 200 cycles at 0.5 C, the capacity is 684.4 mAh g⁻¹ with the fading rate of only 0.251% per cycle. Additionally, the MoO₃ modification provides good surface protection of lithium anode and depresses the lithium anode degradation.  相似文献   

    

《Advanced Materials Interfaces》2018,5(16)

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Khang Ngoc Dinh  Penglun Zheng  Zhengfei Dai  Yu Zhang  Raksha Dangol  Yun Zheng  Bing Li  Yun Zong  Qingyu Yan 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(8)

Herein, the hydrothermal synthesis of porous ultrathin ternary NiFeV layer double hydroxides (LDHs) nanosheets grown on Nickel foam (NF) substrate as a highly efficient electrode toward overall water splitting in alkaline media is reported. The lateral size of the nanosheets is about a few hundreds of nanometers with the thickness of ≈10 nm. Among all molar ratios investigated, the Ni_0.75Fe_0.125V_0.125‐LDHs/NF electrode depicts the optimized performance. It displays an excellent catalytic activity with a modest overpotential of 231 mV for the oxygen evolution reaction (OER) and 125 mV for the hydrogen evolution reaction (HER) in 1.0 m KOH electrolyte. Its exceptional activity is further shown in its small Tafel slope of 39.4 and 62.0 mV dec^?1 for OER and HER, respectively. More importantly, remarkable durability and stability are also observed. When used for overall water splitting, the Ni_0.75Fe_0.125V_0.125‐LDHs/NF electrodes require a voltage of only 1.591 V to reach 10 mA cm^?2 in alkaline solution. These outstanding performances are mainly attributed to the synergistic effect of the ternary metal system that boosts the intrinsic catalytic activity and active surface area. This work explores a promising way to achieve the optimal inexpensive Ni‐based hydroxide electrocatalyst for overall water splitting.  相似文献   

    

Can Wu  Dan Liu  Hui Li  Jinghong Li 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(16)

Electrocatalytic hydrogen evolution reaction (HER) based on water splitting holds great promise for clean energy technologies, in which the key issue is exploring cost‐effective materials to replace noble metal catalysts. Here, a sequential chemical etching and pyrolysis strategy are developed to prepare molybdenum carbide‐decorated metallic cobalt@nitrogen‐doped porous carbon polyhedrons (denoted as Mo/Co@N–C) hybrids for enhanced electrocatalytic hydrogen evolution. The obtained metallic Co nanoparticles are coated by N‐doped carbon thin layers while the formed molybdenum carbide nanoparticles are well‐dispersed in the whole Co@N–C frames. Benefiting from the additionally implanted molybdenum carbide active sites, the HER performance of Mo/Co@N–C hybrids is significantly promoted compared with the single Co@N–C that is derived from the pristine ZIF‐67 both in alkaline and acidic media. As a result, the as‐synthesized Mo/Co@N–C hybrids exhibit superior HER electrocatalytic activity, and only very low overpotentials of 157 and 187 mV are needed at 10 mA cm^?2 in 1 m KOH and 0.5 m H₂SO₄, respectively, opening a door for rational design and fabrication of novel low‐cost electrocatalysts with hierarchical structures toward electrochemical energy storage and conversion.  相似文献