Electrochemical nitrogen reduction reaction (eNRR) is recognized as a promising approach for ammonia synthesis, which is, however, impeded by the inert nitrogen and the unavoidable competing hydrogen evolution reaction (HER). Here, a Mo-PTA@CNT electrocatalyst in which Mo species are anchored on the fourfold hollow sites of phosphotungstic acid (PTA) and closely embedded in multi-walled carbon nanotubes (CNT) for immobilization is designed and synthesized. Interestingly, the catalyst presents a high ammonia yield rate of 51 ± 1 µg h −1 mg cat.−1 and an excellent Faradaic efficiency of 83 ± 1% at −0.1 V versus RHE under ambient conditions. The concentrations of NH 4 + are also quantitatively calculated by 1 H NMR spectra and ion chromatography. Isotopic labeling identifies that the N atom of the formed NH 3 originates from N 2 . The controlled experiments confirm a strong interaction between Mo-PTA and N 2 with an adsorption energy of 50.46 kJ mol −1 and activation energy of 21.36 kJ mol −1 . More importantly, due to CNT's gas storage and hydrophobicity properties, there is a fourfold increase in N 2 content. The concentration of H 2 O is reduced by more than half at the interface of the electrode. Thus, the activity of eNRR can be significantly improved with ultrahigh electron selectivity.

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Main group single atom catalysts (SACs) are promising for CO2 electroreduction to CO by virtue of their ability in preventing the hydrogen evolution reaction and CO poisoning. Unfortunately, their delocalized orbitals reduce the CO2 activation to *COOH. Herein, an O doping strategy to localize electrons on p‐orbitals through asymmetric coordination of Ca SAC sites (Ca‐N3O) is developed, thus enhancing the CO2 activation. Theoretical calculations indicate that asymmetric coordination of Ca‐N3O improves electron‐localization around Ca sites and thus promotes *COOH formation. X‐ray absorption fine spectroscopy shows the obtained Ca‐N3O features: one O and three N coordinated atoms with one Ca as a reactive site. In situ attenuated total reflection infrared spectroscopy proves that Ca‐N3O promotes *COOH formation. As a result, the Ca‐N3O catalyst exhibits a state‐of‐the‐art turnover frequency of ≈15 000 per hour in an H‐cell and a large current density of −400 mA cm−2 with a CO Faradaic efficiency (FE) ≥ 90% in a flow cell. Moreover, Ca‐N3O sites retain a FE above 90% even with a 30% diluted CO2 concentration.

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Photoelectrochemical (PEC) water splitting is a promising approach for renewable solar light conversion. However, surface Fermi level pinning (FLP), caused by surface trap states, severely restricts the PEC activities. Theoretical calculations indicate subsurface oxygen vacancy (sub‐Ov) could release the FLP and retain the active structure. A series of metal oxide semiconductors with sub‐Ov were prepared through precisely regulated spin‐coating and calcination. Etching X‐ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), and electron energy loss spectra (EELS) demonstrated Ov located at sub ∼2–5 nm region. Mott–Schottky and open circuit photovoltage results confirmed the surface trap states elimination and Fermi level de‐pinning. Thus, superior PEC performances of 5.1, 3.4, and 2.1 mA cm−2 at 1.23 V vs. RHE were achieved on BiVO4, Bi2O3, TiO2 with outstanding stability for 72 h, outperforming most reported works under the identical conditions.

The difficulty of adsorption and activation of CO2 at the catalytic site and rapid recombination of photogenerated charge carriers severely restrict the CO2 conversion efficiency. Here, we fabricate a novel alkaline Co­(OH)2-decorated ultrathin 2D titanic acid nanosheet (H2Ti6O13) catalyst, which rationally couples the structural and functional merits of ultrathin 2D supports with catalytically active Co species. Alkaline Co­(OH)2 beneficially binds and activates CO2 molecules, while monolayer H2Ti6O13 acts as an electron relay that bridges a photosensitizer with Co­(OH)2 catalytic sites. As such, photoexcited charges can be efficiently channeled from light absorbers to activated CO2 molecules through the ultrathin hybrid Co­(OH)2/H2Ti6O13 composite, thereby producing syngas (CO/H2 mixture) from photoreduction of CO2. High evolution rates of 56.5 μmol h–1 for CO and 59.3 μmol h–1 for H2 are achieved over optimal Co­(OH)2/H2Ti6O13 by visible light illumination. In addition, the CO/H2 ratio can be facilely tuned from 1:1 to 1:2.4 by changing the Co­(OH)2 content, thus presenting a feasible approach to controllably synthesize different H2/CO mixtures for target applications.

Electrocatalytic N 2 reduction reaction (eNRR) provides a promising carbonneutral and sustainable ammonia-synthesizing alternative to the Haber-Bosch process. However, the nonpolar N 2 has significant thermodynamic stability and requires ultrahigh energy to break down the N�N bond. Here, we report the construction of local enhanced electric fields (LEEFs) by Ag nanoneedle arrays to promote N�N fracture thus assisting the eNRR. The LEEFs could induce charge polarization on nitrogen atoms and reduce the energy barrier in the N 2 first-protonation step. The detected N�N and N�H intermediates prove the cleavage of the N�N bond and the hydrogenation of N 2 by LEEFs. The increased LEEFs lead to logarithmic growth rates for the targeted eNRR and exponential growth rates for the unavoidable competitive hydrogen evolution reaction. Thus, regulation and tuning of LEEFs to ∼4 × 10 4 kV m −1 endows the raise of eNRR to the summit, achieving high ammonia selectivity with a Faradaic efficiency of 72.3 ± 4.0%.