To meet the requirements of potential applications, it is of great importance to explore new catalysts for formic acid oxidation that have both ultra-high mass activity and CO resistance. Here, we ...successfully synthesize atomically dispersed Rh on N-doped carbon (SA-Rh/CN) and discover that SA-Rh/CN exhibits promising electrocatalytic properties for formic acid oxidation. The mass activity shows 28- and 67-fold enhancements compared with state-of-the-art Pd/C and Pt/C, respectively, despite the low activity of Rh/C. Interestingly, SA-Rh/CN exhibits greatly enhanced tolerance to CO poisoning, and Rh atoms in SA-Rh/CN resist sintering after long-term testing, resulting in excellent catalytic stability. Density functional theory calculations suggest that the formate route is more favourable on SA-Rh/CN. According to calculations, the high barrier to produce CO, together with the relatively unfavourable binding with CO, contribute to its CO tolerance.
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The low catalytic kinetics of many non-precious electrocatalysts for hydrogen evolution reaction is often associated with their adverse hydrogen adsorption/desorption kinetics. Thus, improving their ...kinetics as well as understanding the mechanism is critically important. Herein, the strategy of utilizing unique ethylene glycol ligand environments was employed to circumvent the aforesaid kinetic limitations in the composites of Pt-loaded CoP linked by ethylene-glycol through proton concentration and hydrogen spillover. At a low Pt loading of 1.5 wt%, the catalytic performance was significantly improved with dramatically decreased Tafel slopes from 104.6 mV dec
−1
of CoP to 42.5 mV dec
−1
. Control experiments and theoretical calculations revealed that ethylene-glycol concentrated hydrogen intermediates at Pt (>7.3 times), facilitated the hydrogen spillover from hydrogen-enriched Pt to hydrogen-deficient CoP and modulated the local electronic structures to afford thermo-neutral Pt/CoP interfacial sites, improving the catalytic kinetics ultimately. The composites with 1.5 wt% Pt loading delivered a low overpotential of 21 mV at 10 mA cm
−2
as well as record high noble-metal utilization activity, outperforming commercial Pt/C and other hydrogen spillover electrocatalysts for HER. This strategy may provide insights for the design of electrocatalysts.
Unique ethylene glycol ligand environments are utilized to overcome the HER kinetic limitation of CoP modified by a low Pt loading
via
local proton concentration and subsequent hydrogen spillover.
Searching the high‐efficient, stable, and earth‐abundant electrocatalysts to replace the precious noble metals holds the promise for practical utilizations of hydrogen and oxygen evolution reactions ...(HER and OER). Here, a series of highly active and robust Co‐doped nickel phosphides (Ni2−xCoxP) catalysts and their hybrids with reduced graphene oxide (rGO) are developed as bifunctional catalysts for both HER and OER. The Co‐doping in Ni2P and their hybridization with rGO effectively regulate the catalytic activity of the surface active sites, accelerate the charge transfer, and boost their superior catalytic activity. Density functional theory calculations show that the Co‐doped catalysts deliver the moderate trapping of atomic hydrogen and facile desorption of the generated H2 due to the H‐poisoned surface active sites of Ni2−xCoxP under the real catalytic process. Electrochemical measurements reveal the high HER efficiency and durability of the NiCoP/rGO hybrids in electrolytes with pH 0–14. Coupled with the remarkable and robust OER activity of the NiCoP/rGO hybrids, the practical utilization of the NiCoP/rGO‖NiCoP/rGO for overall water splitting yields a catalytic current density of 10 mA cm−2 at 1.59 V over 75 h without an obvious degradation and Faradic efficiency of ≈100% in a two‐electrode configuration and 1.0 m KOH.
Co‐doped nickel phosphide catalysts and their hybrids with reduced graphene oxide exhibit robust electrocatalytic activity toward both the hydrogen evolution reaction and the oxygen evolution reaction. Density functional theory calculations reveal that the Co chemical doping moderates trapping of atomic hydrogen and facile desorption of H2 when the most chemically active part of the surface is poisoned by hydrogen under the catalytic process.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The alkylation of ketones or secondary alcohols using alcohols as alkylating agents via hydrogen borrowing strategy presents a powerful method for the synthesis of ɑ‐alkylated ketones. In this ...review, we summarize the progress catalyzed by Ir, Pd, Rh, Ru, Mn, Fe, Co, Ni, and Cu catalysts for the α‐alkylation of ketones with alcohols and cross‐coupling of secondary alcohols with alcohols from 2017 to 2021. A wide range of ketones (aromatic and aliphatic ketones) and alcohols (benzylic and aliphatic primary alcohols, aromatic and aliphatic secondary alcohols, alkenyl alcohols, and diols) are well tolerated. Furthermore, we also discuss current challenges and propose perspectives on the coming development in this filed. The objective of the present review is to give an overview on recent advances for α‐alkylation of ketones with alcohols and β‐alkylation of secondary alcohols with alcohols. Finally, we hope that this review will give inspirations on alkylation of ketones or secondary alcohols with alcohols.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The selective hydrogenation of CO
to value-added chemicals is attractive but still challenged by the high-performance catalyst. In this work, we report that gallium nitride (GaN) catalyzes the direct ...hydrogenation of CO
to dimethyl ether (DME) with a CO-free selectivity of about 80%. The activity of GaN for the hydrogenation of CO
is much higher than that for the hydrogenation of CO although the product distribution is very similar. The steady-state and transient experimental results, spectroscopic studies, and density functional theory calculations rigorously reveal that DME is produced as the primary product via the methyl and formate intermediates, which are formed over different planes of GaN with similar activation energies. This essentially differs from the traditional DME synthesis via the methanol intermediate over a hybrid catalyst. The present work offers a different catalyst capable of the direct hydrogenation of CO
to DME and thus enriches the chemistry for CO
transformations.
Abstract
Methane (CH
4
) oxidation to high value chemicals under mild conditions through photocatalysis is a sustainable and appealing pathway, nevertheless confronting the critical issues regarding ...both conversion and selectivity. Herein, under visible irradiation (420 nm), the synergy of palladium (Pd) atom cocatalyst and oxygen vacancies (OVs) on In
2
O
3
nanorods enables superior photocatalytic CH
4
activation by O
2
. The optimized catalyst reaches ca. 100 μmol h
−1
of C1 oxygenates, with a selectivity of primary products (CH
3
OH and CH
3
OOH) up to 82.5%. Mechanism investigation elucidates that such superior photocatalysis is induced by the dedicated function of Pd single atoms and oxygen vacancies on boosting hole and electron transfer, respectively. O
2
is proven to be the only oxygen source for CH
3
OH production, while H
2
O acts as the promoter for efficient CH
4
activation through ·OH production and facilitates product desorption as indicated by DFT modeling. This work thus provides new understandings on simultaneous regulation of both activity and selectivity by the synergy of single atom cocatalysts and oxygen vacancies.
The coordinated configuration of atomic platinum (Pt) has always been identified as an active site with high intrinsic activity for hydrogen evolution reaction (HER). Herein, we purposely synthesize ...single vacancies in a carbon matrix (defective graphene) that can trap atomic Pt to form the Pt–C3 configuration, which gives exceptionally high reactivity for HER in both acidic and alkaline solutions. The intrinsic activity of Pt–C3 site is valued with a turnover frequency (TOF) of 26.41 s–1 and mass activity of 26.05 A g–1 at 100 mV, respectively, which are both nearly 18 times higher than those of commercial 20 wt % Pt/C. It is revealed that the optimal coordination Pt–C3 has a stronger electron-capture ability and lower Gibbs free energy difference (ΔG), resulting in promoting the reduction of adsorbed H+ and the acceleration of H2 desorption, thus exhibiting the extraordinary HER activity. This work provides a new insight on the unique coordinated configuration of dispersive atomic Pt in defective C matrix for superior HER performance.
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IJS, KILJ, NUK, PNG, UL, UM
Abstract
Identification on catalytic sites of heterogeneous catalysts at atomic level is important to understand catalytic mechanism. Surface engineering on defects of metal oxides can construct new ...active sites and regulate catalytic activity and selectivity. Here we outline the strategy by controlling surface defects of nanoceria to create the solid frustrated Lewis pair (FLP) metal oxide for efficient hydrogenation of alkenes and alkynes. Porous nanorods of ceria (
PN
-CeO
2
) with a high concentration of surface defects construct new Lewis acidic sites by two adjacent surface Ce
3+
. The neighbouring surface lattice oxygen as Lewis base and constructed Lewis acid create solid FLP site due to the rigid lattice of ceria, which can easily dissociate H–H bond with low activation energy of 0.17 eV.
Development of convenient and effective heterogeneous non-noble metal catalysts for α-alkylation of ketones with alcohols is challenging in heterogeneous catalysis. Here, we report active non-noble ...metal Cu/CuOx catalysts for the construction of C-C bonds by the α-alkylation of ketones with alcohols through the borrowing hydrogen methodology. The optimal Cu/CuOx-250 catalyst exhibits good catalytic performance in the reactions to give the corresponding products in 50-96% yields. The Cu/CuOx catalysts are characterized by different analysis techniques such as XRD, TEM, XPS, H
2
-TPR, BET, and ICP. Moreover, the catalyst can be reused at least for five successive cycles without significant loss of activity. The present study provides meaningful insights into the development of non-noble metal heterogeneous catalysts for α-alkylation of ketones with alcohols.
An active heterogeneous non-noble metal Cu/CuOx catalyst was prepared by reduction of calcined CuO in hydrogen flow at different temperatures and applied in α-alkylation of ketones with primary alcohols to give the alkylated products in 50-96% yields.
Sub-nanometric Pd clusters on porous nanorods of CeO2 (PN-CeO2) with a high Pd dispersion of 73.6% exhibit the highest catalytic activity and best chemoselectivity for hydrogenation of nitroarenes to ...date. For hydrogenation of 4-nitrophenol, the catalysts yield a TOF of ∼44059 h–1 and a chemoselectivity to 4-aminophenol of >99.9%. The superior catalytic performance can be attributed to a cooperative effect between the highly dispersed sub-nanometric Pd clusters for hydrogen activation and unique surface sites of PN-CeO2 with a high concentration of oxygen vacancy for an energetically and geometrically preferential adsorption of nitroarenes via nitro group. The high concentration of surface defects of PN-CeO2 and large Pd dispersion contribute to the enhanced catalytic activity for the hydrogenation reactions. The high chemoselectivity is mainly governed by the high Pd dispersion on the support. The catalysts also deliver high catalytic activity and selectivity for nitroaromatics with various reducible substituents into the corresponding aminoarenes.
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IJS, KILJ, NUK, PNG, UL, UM
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