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1.
The electrochemical nitrogen reduction reaction (NRR) is a promising energy-efficient and low-emission alternative to the traditional Haber–Bosch process. Usually, the competing hydrogen evolution reaction (HER) and the reaction barrier of ambient electrochemical NRR are significant challenges, making a simultaneous high NH3 formation rate and high Faradic efficiency (FE) difficult. To give effective NRR electrocatalysis and suppressed HER, the surface atomic structure of W18O49, which has exposed active W sites and weak binding for H2, is doped with Fe. A high NH3 formation rate of 24.7 μg h−1 mgcat−1 and a high FE of 20.0 % are achieved at an overpotential of only −0.15 V versus the reversible hydrogen electrode. Ab initio calculations reveal an intercalation-type doping of Fe atoms in the tunnels of the W18O49 crystal structure, which increases the oxygen vacancies and exposes more W active sites, optimizes the nitrogen adsorption energy, and facilitates the electrocatalytic NRR.  相似文献   

2.
The electrochemical nitrogen reduction reaction (NRR) offers a sustainable solution towards ammonia production but suffers poor reaction performance owing to preferential catalyst–H formation and the consequential hydrogen evolution reaction (HER). Now, the Pt/Au electrocatalyst d‐band structure is electronically modified using zeolitic imidazole framework (ZIF) to achieve a Faradaic efficiency (FE) of >44 % with high ammonia yield rate of >161 μg mgcat?1 h?1 under ambient conditions. The strategy lowers electrocatalyst d‐band position to weaken H adsorption and concurrently creates electron‐deficient sites to kinetically drive NRR by promoting catalyst–N2 interaction. The ZIF coating on the electrocatalyst doubles as a hydrophobic layer to suppress HER, further improving FE by >44‐fold compared to without ZIF (ca. 1 %). The Pt/Au‐NZIF interaction is key to enable strong N2 adsorption over H atom.  相似文献   

3.
Electrochemical N2 reduction reactions (NRR) and the N2 oxidation reaction (NOR), using H2O and N2, are a sustainable approach to N2 fixation. To date, owing to the chemical inertness of nitrogen, emerging electrocatalysts for the electrochemical NRR and NOR at room temperature and atmospheric pressure remain largely underexplored. Herein, a new‐type Fe‐SnO2 was designed as a Janus electrocatalyst for achieving highly efficient NRR and NOR catalysis. A high NH3 yield of 82.7 μg h?1 mgcat.?1 and a Faraday efficiency (FE) of 20.4 % were obtained for NRR. This catalyst can also serve as an excellent NOR electrocatalyst with a NO3? yields of 42.9 μg h?1 mgcat.?1 and a FE of 0.84 %. By means of experiments and DFT calculations, it is revealed that the oxygen vacancy‐anchored single‐atom Fe can effectively adsorb and activate chemical inert N2 molecules, lowering the energy barrier for the vital breakage of N≡N and resulting in the enhanced N2 fixation performance.  相似文献   

4.
Titanium‐based catalysts are needed to achieve electrocatalytic N2 reduction to NH3 with a large NH3 yield and a high Faradaic efficiency (FE). One of the cheapest and most abundant metals on earth, iron, is an effective dopant for greatly improving the nitrogen reduction reaction (NRR) performance of TiO2 nanoparticles in ambient N2‐to‐NH3 conversion. In 0.5 m LiClO4, Fe‐doped TiO2 catalyst attains a high FE of 25.6 % and a large NH3 yield of 25.47 μg h?1 mgcat?1 at ?0.40 V versus a reversible hydrogen electrode. This performance compares favorably to those of all previously reported titanium‐ and iron‐based NRR electrocatalysts in aqueous media. The catalytic mechanism is further probed with theoretical calculations.  相似文献   

5.
Crystal phase engineering is a powerful strategy for regulating the performance of electrocatalysts towards many electrocatalytic reactions, while its impact on the nitrogen electroreduction has been largely unexplored. Herein, we demonstrate that structurally ordered body‐centered cubic (BCC) PdCu nanoparticles can be adopted as active, selective, and stable electrocatalysts for ammonia synthesis. Specifically, the BCC PdCu exhibits excellent activity with a high NH3 yield of 35.7 μg h?1 mg?1cat, Faradaic efficiency of 11.5 %, and high selectivity (no N2H4 is detected) at ?0.1 V versus reversible hydrogen electrode, outperforming its counterpart, face‐centered cubic (FCC) PdCu, and most reported nitrogen reduction reaction (NRR) electrocatalysts. It also exhibits durable stability for consecutive electrolysis for five cycles. Density functional theory calculation reveals that strong orbital interactions between Pd and neighboring Cu sites in BCC PdCu obtained by structure engineering induces an evident correlation effect for boosting up the Pd 4d electronic activities for efficient NRR catalysis. Our findings open up a new avenue for designing active and stable electrocatalysts towards NRR.  相似文献   

6.
Surface regulation is an effective strategy to improve the performance of catalysts, but it has been rarely demonstrated for nitrogen reduction reaction (NRR) to date. Now, surface‐rough Rh2Sb nanorod (RNR) and surface‐smooth Rh2Sb NR (SNR) were selectively created, and their performance for NRR was investigated. The high‐index‐facet bounded Rh2Sb RNRs/C exhibit a high NH3 yield rate of 228.85±12.96 μg h?1 mg?1Rh at ?0.45 V versus reversible hydrogen electrode (RHE), outperforming the Rh2Sb SNRs/C (63.07±4.45 μg h?1 mg?1Rh) and Rh nanoparticles/C (22.82±1.49 μg h?1 mg?1Rh), owing to the enhanced adsorption and activation of N2 on high‐index facets. Rh2Sb RNRs/C also show durable stability with negligible activity decay after 10 h of successive electrolysis. The present work demonstrates that surface regulation plays an important role in promoting NRR activity and provides a new strategy for creating efficient NRR electrocatalysts.  相似文献   

7.
The (photo)electrochemical N2 reduction reaction (NRR) provides a favorable avenue for the production of NH3 using renewable energy in mild operating conditions. Understanding and building an efficient catalyst with high NH3 selectivity represents an area of intense interest for the early stages of development for NRR. Herein, we introduce a CoOx layer to tune the local electronic structure of Au nanoparticles with positive valence sites for boosting conversion of N2 to NH3. The catalysts, possessing high average oxidation states (ca. 40 %), achieve a high NH3 yield rate of 15.1 μg cm?2 h?1 and a good faradic efficiency of 19 % at ?0.5 V versus reversible hydrogen electrode. Experimental results and simulations reveal that the ability to tune the oxidation state of Au enables the control of N2 adsorption and the concomitant energy barrier of NRR. Altering the Au oxidation state provides a unique strategy for control of NRR in the production of valuable NH3.  相似文献   

8.
N2 fixation by the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions is regarded as a potential approach to achieve NH3 production, which still heavily relies on the Haber–Bosch process at the cost of huge energy and massive production of CO2. A noble‐metal‐free Bi4V2O11/CeO2 hybrid with an amorphous phase (BVC‐A) is used as the cathode for electrocatalytic NRR. The amorphous Bi4V2O11 contains significant defects, which play a role as active sites. The CeO2 not only serves as a trigger to induce the amorphous structure, but also establishes band alignment with Bi4V2O11 for rapid interfacial charge transfer. Remarkably, BVC‐A shows outstanding electrocatalytic NRR performance with high average yield (NH3: 23.21 μg h?1 mg?1cat., Faradaic efficiency: 10.16 %) under ambient conditions, which is superior to the Bi4V2O11/CeO2 hybrid with crystalline phase (BVC‐C) counterpart.  相似文献   

9.
Phosphorus‐modified tungsten nitride/reduced graphene oxide (P‐WN/rGO) is designed as a high‐efficient, low‐cost electrocatalyst for the hydrogen evolution reaction (HER). WN (ca. 3 nm in size) on rGO is first synthesized by using the H3[PO4(W3O9)4] cluster as a W source. Followed by phosphorization, the particle size increase slightly to about 4 nm with a P content of 2.52 at %. The interaction of P with rGO and WN results in an obvious increase of work function, being close to Pt metal. The P‐WN/rGO exhibits low onset overpotential of 46 mV, Tafel slope of 54 mV dec?1, and a large exchange current density of 0.35 mA cm?2 in acid media. It requires overpotential of only 85 mV at current density of 10 mA cm?2, while remaining good stability in accelerated durability testing. This work shows that the modification with a second anion is powerful way to design new catalysts for HER.  相似文献   

10.
Atomically dispersed Fe was designed on TiO2 and explored as a Janus electrocatalyst for both nitrogen oxidation reaction (NOR) and nitrogen reduction reaction (NRR) in a two-electrode system. Pulsed electrochemical catalysis (PE) was firstly involved to inhibit the competitive hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Excitingly, an unanticipated yield of 7055.81 μmol h−1 g−1cat. and 12 868.33 μmol h−1 g−1cat. were obtained for NOR and NRR at 3.5 V, respectively, 44.94 times and 7.8 times increase in FE than the conventional constant voltage electrocatalytic method. Experiments and density functional theory (DFT) calculations revealed that the single-atom Fe could stabilize the oxygen vacancy, lower the energy barrier for the vital rupture of N≡N, and result in enhanced N2 fixation performance. More importantly, PE could effectively enhance the N2 supply by reducing competitive O2 and H2 agglomeration, inhibit the electrocatalytic by-product formation for longstanding *OOH and *H intermediates, and promote the non-electrocatalytic process of N2 activation.  相似文献   

11.
The electrochemical nitrogen reduction reaction (NRR) offers a sustainable solution towards ammonia production but suffers poor reaction performance owing to preferential catalyst–H formation and the consequential hydrogen evolution reaction (HER). Now, the Pt/Au electrocatalyst d-band structure is electronically modified using zeolitic imidazole framework (ZIF) to achieve a Faradaic efficiency (FE) of >44 % with high ammonia yield rate of >161 μg mgcat−1 h−1 under ambient conditions. The strategy lowers electrocatalyst d-band position to weaken H adsorption and concurrently creates electron-deficient sites to kinetically drive NRR by promoting catalyst–N2 interaction. The ZIF coating on the electrocatalyst doubles as a hydrophobic layer to suppress HER, further improving FE by >44-fold compared to without ZIF (ca. 1 %). The Pt/Au-NZIF interaction is key to enable strong N2 adsorption over H atom.  相似文献   

12.
Vacancy engineering has been proved repeatedly as an adoptable strategy to boost electrocatalysis, while its poor selectivity restricts the usage in nitrogen reduction reaction (NRR) as overwhelming competition from hydrogen evolution reaction (HER). Revealed by density functional theory calculations, the selenium vacancy in ReSe2 crystal can enhance its electroactivity for both NRR and HER by shifting the d‐band from ?4.42 to ?4.19 eV. To restrict the HER, we report a novel method by burying selenium vacancy‐rich ReSe2@carbonized bacterial cellulose (Vr‐ReSe2@CBC) nanofibers between two CBC layers, leading to boosted Faradaic efficiency of 42.5 % and ammonia yield of 28.3 μg h?1 cm?2 at a potential of ?0.25 V on an abrupt interface. As demonstrated by the nitrogen bubble adhesive force, superhydrophilic measurements, and COMSOL Multiphysics simulations, the hydrophobic and porous CBC layers can keep the internal Vr‐ReSe2@CBC nanofibers away from water coverage, leaving more unoccupied active sites for the N2 reduction (especially for the potential determining step of proton‐electron coupling and transferring processes as *NN → *NNH).  相似文献   

13.
A core‐shell structure with CuO core and carbon quantum dots (CQDs) and carbon hollow nanospheres (CHNS) shell was prepared through facile in‐situ hydrothermal process. The composite was used for non‐enzymatic hydrogen peroxide sensing and electrochemical overall water splitting. The core‐shell structure was established from the transmission electron microscopy image analysis. Raman and UV‐Vis spectroscopy analysis confirmed the interaction between CuO and CQDs. The electrochemical studies showed the limit of detection and sensitivity of the prepared composite as 2.4 nM and 56.72 μA μM?1 cm?2, respectively. The core‐shell structure facilitated better charge transportation which in turn exhibited elevated electro‐catalysis towards hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting. The overpotential of 159 mV was required to achieve 10 mA cm?2 current density for HER and an overpotential of 322 mV was required to achieve 10 mA cm?2 current density for OER in 1.0 M KOH. A two‐electrode system was constructed for overall water splitting reaction, which showed 10 and 50 mA cm?2 current density at 1.83 and 1.96 V, respectively. The prepared CuO@CQDs@CHNS catalyst demonstrated excellent robustness in HER and OER catalyzing condition along with overall water splitting reaction. Therefore, the CuO@CQDs@CHNS could be considered as promising electro‐catalyst for H2O2 sensing, HER, OER and overall water splitting.  相似文献   

14.
《中国化学快报》2023,34(3):107337
Ammonia is the feedstock chemical for most fertilizers and the alternative of renewable energy carriers. Environmentally benign electrochemical nitrogen reduction reaction (NRR) under mild conditions has been recognized as one of the most attractive strategies for N2 fixation. Herein, inspired by Mo-based nitrogenase, W/Mo-doping electrocatalysts were developed with mixed-metal polyoxometalate H3PW6Mo6O40 as the precursor for high performance electrocatalytic NRR. Trace amount of Pt was transplanted on the surface of W/Mo@rGO via in situ electroplating treatment to further improve the NRR performance. The resulting Pt-W/Mo@rGO-6 achieves excellent performance for NRR with a high NH3 yield of 79.2 µg h?1 mgcat?1 due to the multicomponent synergistic effect in the composite catalyst. The Pt-W/Mo@rGO-6 represents the first example of highly efficient NRR electraocatalyst derived from mixed-metal polyoxometalate, which exhibits outstanding stability confirmed by the constant catalytic performance over 24 h chronoamperometric test. This finding opens a new avenue to construct highly efficient NRR electrocatalyst by employing mixed metal polyoxometalate as the precursor under ambient conditions.  相似文献   

15.
Electroreduction of CO2 to CO powered by renewable electricity is a possible alternative to synthesizing CO from fossil fuel. However, it is very hard to achieve high current density at high faradaic efficiency (FE). Here, the first use of N,P‐co‐doped carbon aerogels (NPCA) to boost CO2 reduction to CO is presented. The FE of CO could reach 99.1 % with a partial current density of ?143.6 mA cm?2, which is one of the highest current densities to date. NPCA has higher electrochemical active area and overall electronic conductivity than that of N‐ or P‐doped carbon aerogels, which favors electron transfer from CO2 to its radical anion or other key intermediates. By control experiments and theoretical calculations, it is found that the pyridinic N was very active for CO2 reduction to CO, and co‐doping of P with N hinder the hydrogen evolution reaction (HER) significantly, and thus the both current density and FE are very high.  相似文献   

16.
Pyrolysis of a bimetallic metal–organic framework (MIL‐88‐Fe/Ni)‐dicyandiamide composite yield a Fe and Ni containing carbonaceous material, which is an efficient bifunctional electrocatalyst for overall water splitting. FeNi3 and NiFe2O4 are found as metallic and metal oxide compounds closely embedded in an N‐doped carbon–carbon nanotube matrix. This hybrid catalyst (Fe‐Ni@NC‐CNTs) significantly promotes the charge transfer efficiency and restrains the corrosion of the metallic catalysts, which is shown in a high OER and HER activity with an overpotential of 274 and 202 mV, respectively at 10 mA cm?2 in alkaline solution. When this bifunctional catalyst was further used for H2 and O2 production in an electrochemical water‐splitting unit, it can operate in ambient conditions with a competitive gas production rate of 1.15 and 0.57 μL s?1 for hydrogen and oxygen, respectively, showing its potential for practical applications.  相似文献   

17.
Single‐atom catalysts have demonstrated their superiority over other types of catalysts for various reactions. However, the reported nitrogen reduction reaction single‐atom electrocatalysts for the nitrogen reduction reaction exclusively utilize metal–nitrogen or metal–carbon coordination configurations as catalytic active sites. Here, we report a Fe single‐atom electrocatalyst supported on low‐cost, nitrogen‐free lignocellulose‐derived carbon. The extended X‐ray absorption fine structure spectra confirm that Fe atoms are anchored to the support via the Fe‐(O‐C2)4 coordination configuration. Density functional theory calculations identify Fe‐(O‐C2)4 as the active site for the nitrogen reduction reaction. An electrode consisting of the electrocatalyst loaded on carbon cloth can afford a NH3 yield rate and faradaic efficiency of 32.1 μg h?1 mgcat.?1 (5350 μg h?1 mgFe?1) and 29.3 %, respectively. An exceptional NH3 yield rate of 307.7 μg h?1 mgcat.?1 (51 283 μg h?1 mgFe?1) with a near record faradaic efficiency of 51.0 % can be achieved with the electrocatalyst immobilized on a glassy carbon electrode.  相似文献   

18.
A nanocomposite of PC/Sb/SbPO4 (PC, phosphorus‐doped carbon) exhibits a high activity and an excellent selectivity for efficient electrocatalytic conversion of N2 to NH3 in both acidic and neutral electrolytes under ambient conditions. At a low reductive potential of ?0.15 V versus the reversible hydrogen electrode (RHE), the PC/Sb/SbPO4 catalyst achieves a high Faradaic efficiency (FE) of 31 % for ammonia production in 0.1 m HCl under mild conditions. In particular, a remarkably high FE value of 34 % is achieved at a lower reductive potential of ?0.1 V (vs. RHE) in a 0.1 m Na2SO4 solution, which is better than most reported electrocatalysts towards the nitrogen reduction reaction (NRR) in neutral electrolyte under mild conditions. The change in surface species and electrocatalytic performance before and after N2 reduction is explored by an ex situ method. PC and SbPO4 are both considered as the active species that enhanced the performance of NRR.  相似文献   

19.
As a metal‐free nitrogen reduction reaction (NRR) photocatalyst, g‐C3N4 is available from a scalable synthesis at low cost. Importantly, it can be readily functionalized to enhance photocatalytic activities. However, the use of g‐C3N4‐based photocatalysts for the NRR has been questioned because of the elusive mechanism and the involvement of N defects. This work reports the synthesis of a g‐C3N4 photocatalyst modified with cyano groups and intercalated K+ (mCNN), possessing extended visible‐light harvesting capacity and superior photocatalytic NRR activity (NH3 yield: 3.42 mmol g?1 h?1). Experimental and theoretical studies suggest that the ‐C≡N in mCNN can be regenerated through a pathway analogous to Mars van Krevelen process with the aid of the intercalated K+. The results confirm that the regeneration of the cyano group not only enhances photocatalytic activity and sustains the catalytic cycle, but also stabilizes the photocatalyst.  相似文献   

20.
Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions provides an intriguing picture for the conversion of N2 into NH3. However, electrocatalytic NRR mainly relies on metal‐based catalysts, and it remains a grand challenge in enabling effective N2 activation on metal‐free catalysts. Here we report a defect engineering strategy to realize effective NRR performance (NH3 yield: 8.09 μg h?1 mg?1cat., Faradaic efficiency: 11.59 %) on metal‐free polymeric carbon nitride (PCN) catalyst. Illustrated by density functional theory calculations, dinitrogen molecule can be chemisorbed on as‐engineered nitrogen vacancies of PCN through constructing a dinuclear end‐on bound structure for spatial electron transfer. Furthermore, the N?N bond length of adsorbed N2 increases dramatically, which corresponds to “strong activation” system to reduce N2 into NH3. This work also highlights the significance of defect engineering for improving electrocatalysts with weak N2 adsorption and activation ability.  相似文献   

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