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An efficient alkoxyl radical-triggered ring expansion/cross-coupling cascade was developed under cheap metal catalysis. Through the metal-catalyzed radical relay strategy, a wide range of medium-sized lactones (9-11 membered) and macrolactones (12, 13, 15, 18, and 19-membered) were constructed in moderate to good yields, along with diverse functional groups including CN, N3, SCN, and X groups installed concurrently. Density functional theory (DFT) calculations revealed that reductive elimination of the cycloalkyl-Cu(iii) species is a more favorable reaction pathway for the cross-coupling step. Based on the results of experiments and DFT, a Cu(i)/Cu(ii)/Cu(iii) catalytic cycle is proposed for this tandem reaction.

We herein report a phosphine-catalyzed (3 + 2) annulation of cyclopropenones with a wide variety of electrophilic π systems, including aldehydes, ketoesters, imines, isocyanates, and carbodiimides, offering products of butenolides, butyrolactams, maleimides, and iminomaleimides, respectively, in high yields with broad substrate scope. An α-ketenyl phosphorous ylide is validated as the key intermediate, which undergoes preferential catalytic cyclization with aldehydes rather than stoichiometric Wittig olefinations. This phosphine-catalyzed activation of cyclopropenones thus supplies a versatile C3 synthon for formal cycloadditon reactions.

Aprotic Li‐CO2 batteries suffer from sluggish solid‐solid co‐oxidation kinetics of C and Li2CO3, requiring extremely high charging potentials and leading to serious side reactions and poor energy efficiency. Herein, we introduce a novel approach to address these challenges by modulating the reaction pathway with tailored Pt d‐electrons and develop an aprotic Li‐CO2 battery with CO and Li2CO3 as the main discharge products. Note that the gas‐solid co‐oxidation reaction between CO and Li2CO3 is both kinetically and thermodynamically more favorable. Consequently, the Li‐CO2 batteries with CoPt alloy‐supported on nitrogen‐doped carbon nanofiber (CoPt@NCNF) cathode exhibit a charging potential of 2.89 V at 50 μA cm−2, which is the lowest charging potential to date. Moreover, the CoPt@NCNF cathode also shows exceptional cycling stability (218 cycles at 50 μA cm−2) and high energy efficiency up to 74.6 %. Comprehensive experiments and theoretical calculations reveal that the lowered d‐band center of CoPt alloy effectively promotes CO desorption and inhibits further CO reduction to C. This work provides promising insights into developing efficient and CO‐selective Li‐CO2 batteries. [ABSTRACT FROM AUTHOR]

Converting CO2 into valuable chemicals has become a widely used research method for CO2 conversion. In this work, the catalytic performance of pyramidal-4Ni catalysts supported on rare earth metal-doped CeO2 toward CO2 reduction reaction (CO2RR) was investigated by using density-functional theory calculations. For rare earth metal-doped CeO2, 2Ce is substituted by 2 trivalent cations and at the same time one oxygen vacancy is created to make charge compensation. We investigated the oxygen vacancy nearest (VO,N) and next-nearest (VO,NN) to 4Ni, and found releasing CO and CO2 dissociation are the rate-determining steps, respectively, via the path of VO,N and VO,NN. Among the studied dopants (Ga, Sb, Lu, Gd, Pr, La, Bi), Gd is identified as the best dopant for catalyzing the reduction of CO2 at 823 K, with the turn-over frequency (TOF) of 104 times as large as that over 4Ni supported on pure CeO2. This exploration pro-vides theoretical support and guidance for the research and application of rare earth metaldoped CeO2-loaded Ni catalysts in the field of CO2 reduction. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER) is an essential process for hydrogen production through water splitting. Atom-doped carbon nanotubes (CNTs) exhibit significant potential in promoting the electrocatalytic HER. By performing density functional theory (DFT) calculations, we have screened HER performance over a series of single atom transition metals (TM = Mo, Rh, Fe, Cr, Co, Zn, Mn, Cu, Ni, Pd) anchored on CNTs (n, n) (n = 5, 10) and graphene (seen as a CNT with the smallest curvature), and found the volcano curves between the adsorption free energy of H* (ΔGH*) and the current density for the HER, yielding the RhN4 catalyst at the peak of the volcano and even with a current density higher than that of Pt when the curvature is smaller than (10, 10). Then, more detailed DFT calculations were conducted to investigate the effect of curvature of CNTs on tuning the HER activity of RhN4@CNT (n, n) (n = 5–10) catalysts, where ΔGH* decreased with the decrease of the curvature, suggesting CNT-supported single atom catalysts having curvature-switched HER activity. The improved HER activity at a higher curvature arose from the more upshifted d-band center. Creating one single vacancy (5-1DB defect) could further enhance the HER activity of RhN4@CNTs. Our work provides a novel approach to designing HER catalysts with tunable activity and stability. [ABSTRACT FROM AUTHOR]

Ag exhibits high selectivity of electrochemical CO 2 reduction (CO 2 R) toward C 1 products, while the hydrogenation involving the concerted proton-electron transfer (CPET) or sequential electron-proton transfer (SEPT) mechanism is still in debate. Toward a better understanding of the Ag-catalyzed electrochemical CO 2 R, we employed a microkinetic model based on the Marcus electron transfer theory to thoroughly investigate the selectivity of C 1 products of electrochemical CO 2 R over the Ag(111) surface. We found that at an acidic condition of pH = 1.94, formate is the main product when U < -0.94 V via the CPET mechanism, whereas CO becomes the primary product when U > -0.94 V via the SEPT mechanism. Conversely, at an alkaline condition of pH = 13.95, formate is the main product following the SEPT mechanism. Our findings provide novel insights into the influence of external factors (applied potential and pH) on the product selectivity and hydrogenation mechanism of electrochemical CO 2 R.