The efficiency of splitting water into hydrogen and oxygen is highly dependent on the catalyst used. Herein, ultrathin Ni(0)‐embedded Ni(OH)2 heterostructured nanosheets, referred to as Ni/Ni(OH)2 ...nanosheets, with superior water splitting activity are synthesized by a partial reduction strategy. This synthetic strategy confers the heterostructured Ni/Ni(OH)2 nanosheets with abundant Ni(0)‐Ni(II) active interfaces for hydrogen evolution reaction (HER) and Ni(II) defects as transitional active sites for oxygen evolution reaction (OER). The obtained Ni/Ni(OH)2 nanosheets exhibit noble metal‐like electrocatalytic activities toward overall water splitting in alkaline condition, to offer 10 mA cm−2 in HER and OER, the required overpotentials are only 77 and 270 mV, respectively. Based on such an outstanding activity, a water splitting electrolysis cell using the Ni/Ni(OH)2 nanosheets as the cathode and anode electrocatalysts has been successfully built. When the output voltage of the electrolytic cell is 1.59 V, a current density of 10 mA cm−2 can be obtained. Moreover, the durability of Ni/Ni(OH)2 nanosheets in the alkaline electrolyte is much better than that of noble metals. No obvious performance decay is observed after 20 h of catalysis. This facile strategy paves the way for designing highly active non‐precious‐metal catalyst to generate both hydrogen and oxygen by electrolyzing water at room temperature.
Heterostructured Ni/Ni(OH)2 nanosheets synthesized using a partial reduction strategy are used as an efficient multifunctional electrocatalyst for the hydrogen evolution reaction, the oxygen evolution reaction, and overall water splitting. This work opens up new opportunities in the rational design of cost‐effective and highly efficient multifunctional electrocatalysts for renewable energy conversion.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The valorization of carbon dioxide (CO2) to fine chemicals is one of the most promising approaches for CO2 capture and utilization. Herein we demonstrated a series of porous organometallic polymers ...could be employed as highly efficient and recyclable catalysts for this purpose. Synergetic effects of specific surface area, iridium content, and CO2 adsorption capability are crucial to achieve excellent selectivity and yields towards N‐formylation of diverse amines with CO2 and H2 under mild reaction conditions even at 20 ppm catalyst loading. Density functional theory calculations revealed not only a redox‐neutral catalytic pathway but also a new plausible mechanism with the incorporation of the key intermediate formic acid via a proton‐relay process. Remarkably, a record turnover number (TON=1.58×106) was achieved in the synthesis of N,N‐dimethylformamide (DMF), and the solid catalysts can be reused up to 12 runs, highlighting their practical potential in industry.
Porous organometallic polymers (POMPs) with controllable porosity and enhanced CO2 adsorption capability were fabricated via the direct knitting strategy. Excellent selectivity and activity with a record turnover number (TON=1.58×106) in the N‐formylation reaction with CO2 and H2 to N,N‐dimethylformamide (DMF) were achieved under mild reaction conditions, and the POMPs could be reused up to 12 runs.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Developing efficient bifunctional electrocatalysts for overall water splitting in acidic conditions is the essential step for proton exchange membrane water electrolyzers (PEMWEs). We first report ...the synthesis of core–shell structure nanoparticles (NPs) with an Au core and an AuIr2 alloy shell (Au@AuIr2). Au@AuIr2 displayed 4.6 (5.6) times higher intrinsic (mass) activity toward the oxygen evolution reaction (OER) than a commercial Ir catalyst. Furthermore, it showed hydrogen evolution reaction (HER) catalytic properties comparable to those of commercial Pt/C. Significantly, when Au@AuIr2 was used as both the anode and cathode catalyst, the overall water splitting cell achieved 10 mA/cm2 with a low cell voltage of 1.55 V and maintained this activity for more than 40 h, which greatly outperformed the commercial couples (Ir/C||Pt/C, 1.63 V, activity decreased within minutes) and is among the most efficient bifunctional catalysts reported. Theoretical calculations coupled with X-ray-based structural analyses suggest that partially oxidized surfaces originating from the electronic interaction between Au and Ir provide a balance for different intermediates binding and realize significantly enhanced OER performance.
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IJS, KILJ, NUK, PNG, UL, UM
An atom‐economic approach that has an unprecedented high selectivity for the synthesis of lactic acid (LA) based on a catalytic dehydrogenative cross‐coupling by using inexpensive bulk ethylene ...glycol and methanol is described. This method relies on the synthesis and utilization of a novel iridium catalyst bearing three N‐heterocyclic carbenes derived from 1,3‐dimethylbenzimidazolium salts, and exhibits outstanding activity in the production of LA turnover frequency (TOF) up to 3660 h−1 owing to an elegant metal–ligand cooperation.
Good things come in threes: An unprecedented dehydrogenative C−C cross‐coupling with inexpensive bulk ethylene glycol and methanol has been developed by using a novel iridium catalyst bearing three N‐heterocyclic carbenes (NHCs). This procedure represents a highly selective and atom‐economic approach for the synthesis of lactic acid (TOF up to 3660 h−1). TOF=turnover frequency; TON=turnover number.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Supported single‐atom catalysts have been emerging as promising materials in a variety of energy catalysis applications. However, studying the role of metal–support interactions at the molecular ...level remains a major challenge, primarily due to the lack of precise atomic structures. In this work, by replacing the frequently used TiO2 support with its molecular analogue, titanium‐oxo cluster (TOC), we successfully produced a new kind of Ti‐O material doped with single silver sites. The as‐obtained Ag10Ti28 cluster, containing four exposed and six embedded Ag sites, is the largest noble‐metal‐doped Ti‐O cluster reported to date. Density functional theory (DFT) calculations show that the Ag10Ti28 core exhibits properties distinct from those of metallic Ag‐based materials. This Ti‐O material doped with single Ag sites presents a high ϵd and moderate CO binding capacity comparable to that of metallic Cu‐based catalysts, suggesting that it might display different catalytic performance from the common Ag‐based catalysts, for example, for CO2 reduction. These results prove that the synergism of active surface metal atoms and the Ti‐O cluster support result in unique physical properties, which might open a new direction for single‐atom‐included catalysts.
Advantageous conjunction: The largest noble‐metal‐doped Ti‐O cluster, Ag10Ti28‐oxo, contains single silver sites. The synergism between the active surface metal atom and the Ti‐O cluster support produces unique electronic properties that are distinct from those of metallic Ag‐based materials.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The global demand for lactic acid (LA) is increasing due to its successful application as monomer for the manufacture of bioplastics. Although N‐heterocyclic carbene (NHC) iridium complexes are ...promising molecular catalysts for LA synthesis, their instabilities have hindered their utilization especially in commercial applications. Here, we report that a porous self‐supported NHC‐iridium coordination polymer can efficiently prevent the clusterization of corresponding NHC‐Ir molecules and can function as a solid molecular recyclable catalyst for dehydrogenation of bio‐polyols to form LA with excellent activity (97 %) and selectivity (>99 %). A turnover number of up to 5700 could be achieved in a single batch, due to the synergistic participation of the Ba2+ and hydroxide ions, as well as the blockage of unwanted pathways by adding methanol. Our findings demonstrate a potential route for the industrial production of LA from cheap and abundant bio‐polyols, including sorbitol.
Bio‐polyols conversion: A series of 3D porous self‐supported NHC‐iridium coordination polymers were prepared and could function as recyclable solid molecular catalysts for dehydrogenation of bio‐polyols to lactic acid with excellent activity and selectivity due to the synergistic participation of the Ba2+ and hydroxide ions, as well as the blockage of unwanted pathways by adding methanol.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Sodium metal batteries (NMBs) have attracted increasing attention as next‐generation rechargeable batteries. How to improve their cycling stability and safety under limited sodium excess conditions, ...ideally zero sodium excess (i.e., anode‐free architecture), is highly desired yet remains challenging. Herein, it is demonstrated that sodium formate (HCOONa), one component of the solid electrolyte interphase (SEI) naturally formed on sodium metal anode, is a promising candidate for designing high‐performance artificial SEI layers, which can suppress the sodium dendrite formation and reduce the side reactions between sodium and the electrolyte. Profiting from the HCOONa interface, the Na|Na3V2(PO4)3 battery with a high mass loading of Na3V2(PO4)3 (10 mg cm−2) exhibits a superior cycling stability with an ultralow decay rate of 0.004% per cycle over 800 cycles. More impressively, a single molecular layer of HCOONa in situ formed on commercial copper current collector helps to extend the lifespan of the anode‐free Cu|Na3V2(PO4)3 battery to 400 cycles with 88.2% capacity relation, representing the longest cycle lifetime reported in anode‐free NMBs.
An in situ formed HCOONa interface is proposed to protect sodium metal anodes and construct stable anode‐free sodium metal batteries. The HCOONa interface can suppress the growth of dendrites and reduce the parasitic reaction of the electrolyte, which effectively improves the capacity and cycling stability of anode‐free sodium metal batteries.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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•Competitive hydrogenolysis behavior between –OCH3 and –OH in guaiacol were revealed.•Modified BaO on MoOx/SBA-15 promote phenol adsorbed and catalyze MeOH consumed.•MoOx/ BaO@SBA-15 ...can be used for one-step upgrading the mixed phenolics into arenes.
The bio-oils derived from fast pyrolysis of lignin contain large amount of phenolic components. Owing to the high oxygen content, these bio-oils could not be used as traffic liquid fuels. Hydrodeoxygenation (HDO) was an effective strategy to upgrade these phenolics into high value-added chemicals such as arenes. However, the challenge of upgrading phenolics into arenes lies in selective hydrogenolysis of the oxygen-containing groups (e.g. –OCH3 and –OH) while keeping the unsaturated aromatic rings intact. However, the competitive adsorption behavior of produced intermediates likely inhibits the further HDO of phenol to arenes. In this work, MoOx/SBA-15 with rich oxygen defects was synthesized, which is capable of inducing phenolics adsorbed in a “nonplanar” manner, weakening the intensity of CAr-OR (R = CH3 or H) bonds and preventing the excessive hydrogenation of aromatic rings. In addition, BaO coating was decorated on MoOx/SBA-15 to tune the surface acid-base properties so as to promote the adsorption of phenol and consume MeOH via alkylation reaction with phenol, enhancing guaiacol one-step HDO into benzene and toluene. Based on catalyst evaluation and characterization as well as density functional theory (DFT) calculations, the catalytic mechanism of phenolics HDO reaction over MoOx/BaO@SBA-15 was analyzed and discussed. Current work helps not only gain deep insights into the competitive interaction for mixed phenolics HDO reaction, but also shed light on the design and synthesis of high-efficient HDO catalysts for upgrading crude bio-oils into arenes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
α-Hydroxy acids have attracted broad attention because of their prevalence in bioactive molecules and biodegradable polymers, but their conventional syntheses are usually restricted to aromatic ...substrates, especially, in a stepwise manner. Herein, we disclose the transformation of alkyl and aryl vicinal glycols to α-hydroxy acetates in water under the air atmosphere with our solid self-supported NHC-Ir single-site catalyst. Both aliphatic and aromatic glycols are compatible with a much higher catalytic efficiency in the presence of this solid single-site catalyst than other viable molecular catalysts (93% vs <35%) because of the “isolation effect”. Remarkably, our catalyst could be reused for 20 runs without an obvious loss in catalytic activity and selectivity. Control experiments and density functional theory calculations reveal that the reaction firstly undergoes a dehydrogenation facilitated by the catalyst, and then it proceeds through an unexpected oxidization relay step by oxygen in the air, leading to the α-hydroxy acetate formation. Our protocol can potentially contribute to the valorization of readily available and inexpensive diols.
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Lignin could be depolymerized into large amount of phenolic compounds via fast pyrolysis. The upgrade of phenolic compounds via hydrodeoxygenation (HDO) involves multiple reaction pathways. It is ...challenging to selectively remove the oxygen-containing groups while keeping the aromatic rings intact. In this work, hierarchical Nb2O5 (H–Nb2O5) microspheres with abundant oxygen vacancies were synthesized to anchor the Pd clusters, which is featured with strong metal-support interaction via the electron transfer between Pd species and Nb species. For phenol HDO reaction, the oxygen vacancies were prone to interact with the phenolic hydroxy groups, resulting in phenol molecule adsorbed in a “nonplanar” manner, greatly weakening the CAr-O bonds and averting the ring hydrogenation. Besides, the activated hydrogen atoms on Pd clusters could migrate to the vicinity of oxygen vacancies via spillover, promoting the cleavage of CAr-O bond to obtain benzene. Current work provides a deep insight into the synergetic catalytic mechanism of Pd/H–Nb2O5 catalyst for phenol HDO reaction, and also sheds light on the design and synthesis of high-efficient catalysts in other heterogeneous catalysis fields.
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•Hierarchical Nb2O5 microspheres with oxygen vacancies were synthesized.•Pd/H–Nb2O5 with metal-support interaction avoids the aggregation of Pd clusters.•Phenolic hydroxy occupied the oxygen vacancies in a “nonplanar” adsorption manner.•“Nonplanar” adsorption weakens the CAr-O bond and avoids the ring hydrogenation.•Hydrogen spillover promotes the cleavage of CAr-O bond to produce benzene.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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