The reactivity of the homo-and heteronuclear oxide clusters [XYO 2 ] + (X, Y = Al, Si, Mg) toward methane was studied using Fourier transform ion cyclotron resonance mass spectrometry, in conjunction with high-level quantum mechanical calculations. The most reactive cluster by both experiment and theory is [Al 2 O 2 ] •+ . In its favorable pathway, this cluster abstracts a hydrogen atom by means of proton-coupled electron transfer (PCET) instead of following the conventional hydrogen-atom transfer (HAT) route. This mechanistic choice originates in the strong Lewis acidity of the aluminum site of [Al 2 O 2 ] •+ , which cleaves the C−H bond heterolytically to form an Al−CH 3 entity, while the proton is transferred to the bridging oxygen atom of the cluster ion. In addition, a comparison of the reactivity of heteronuclear and homonuclear oxide clusters [XYO 2 ] + (X, Y = Al, Si, Mg) reveals a striking doping effect by aluminum. Thus, the vacant s−p hybrid orbital on Al acts as an acceptor of the electron pair from methyl anion (CH 3 − ) and is therefore eminently important for bringing about thermal methane activation by PCET. For the Al-doped cluster ions, the spin density at an oxygen atom, which is crucial for the HAT mechanism, acts here as a spectator during the course of the PCET mediated C−H bond cleavage. A diagnostic plot of the deformation energy vis-a-vis the barrier shows the different HAT/PCET reactivity map for the entire series. This is a strong connection to the recently discussed mechanism of oxidative coupling of methane on magnesium oxide surfaces proceeding through Grignard-type intermediates.

The C-H bond activation of methane mediated by a prototypical heteronuclear metal-oxide cluster, [Al2Mg2O5](•+), was investigated by using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) in conjunction with high-level quantum mechanical calculations. Experimentally, hydrogen-atom abstraction from methane by the cluster ion [Al2Mg2O5](•+) takes place at ambient conditions. As to the mechanism, according to our computational findings, both the proton-coupled electron transfer (PCET) and the conventional hydrogen-atom transfer (HAT) are feasible and compete with each other. This is in distinct contrast to the [XYO2](+) (X, Y = Mg, Al, Si) cluster oxide ions which activate methane exclusively via the PCET route (Li, J.; Zhou, S.; Zhang, J.; Schlangen, M.; Weiske, T.; Usharani, D.; Shaik, S.; Schwarz, H. J. Am. Chem. Soc. 2016, 138, 7973-7981). The electronic origins of the mechanistically rather complex reactivity scenarios of the [Al2Mg2O5](•+)/CH4 couple were elucidated. For the PCET mechanism, in which the Lewis acid-base pair [Al(+)-O(-)] of the cluster acts as the active site, a clear correlation has been established between the nature of the transition state, the corresponding barrier height, the Lewis acidity-basicity of the [M(+)-O(-)] unit, as well as the bond order of the M(+)-O(-) bond. Also addressed is the role of the spin and charge distributions of a terminal oxygen radical site in the direct HAT route. The knowledge of the factors that control the reactivity of PCET and HAT pathways not only deepens our mechanistic understanding of metal-oxide mediated C-H bond activation but may also provide guidance for the rational design of catalysts.

Developing highly active and stable nitrogen reduction reaction (NRR) catalysts for NH3 electrosynthesis remains challenging. Herein, an unusual NRR electrocatalyst is reported with a single Zn(I) site supported on hollow porous N‐doped carbon nanofibers (Zn1N–C). The Zn1N–C nanofibers exhibit an outstanding NRR activity with a high NH3 yield rate of ≈16.1 µg NH3 h−1 mgcat−1 at −0.3 V and Faradaic efficiency (FE) of 11.8% in alkaline media, surpassing other previously reported carbon‐based NRR electrocatalysts with transition metals atomically dispersed and nitrogen coordinated (TM‐Nx) sites. 15N2 isotope labeling experiments confirm that the feeding nitrogen gas is the only nitrogen source in the production of NH3. Structural characterization reveals that atomically dispersed Zn(I) sites with Zn–N4 moieties are likely the active sites, and the nearby graphitic N site synergistically facilitates the NRR process. In situ attenuated total reflectance‐Fourier transform infrared measurement and theoretical calculation elucidate that the formation of initial *NNH intermediate is the rate‐limiting step during the NH3 production. The graphitic N atoms adjacent to the tetracoordinate Zn–N4 moieties could significantly lower the energy barrier for this step to accelerate hydrogenation kinetics duing the NRR.

An unexpected mechanistic switch as well as a change of the product distribution in the thermal gas-phase activation of methane have been identified when diatomic [ZnO] is ligated with acetonitrile. Theoretical studies suggest that a strong metal-carbon attraction in the pristine [ZnO] species plays an important role in the rebound of the incipient CH radical to the metal center, thus permitting the competitive generation of CH , OH , and CH OH. This interaction is drastically weakened by a single CH CN ligand. As a result, upon ligation the proton-coupled single electron transfer that prevails for [ZnO] /CH switches to the classical hydrogen-atom-transfer process, thus giving rise to the exclusive expulsion of CH . This ligand effect can be modeled quite well by an oriented external electric field of a negative point charge.

Dynamic interphases provide a general method for achieving energy-dense metal batteries based on earth-abundant anode chemistries.