N2 electroreduction into NH3 represents an attractive prospect for N2 utilization. Nevertheless, this process suffers from low Faraday efficiency (FE) and yield rate for NH3. In this work, a highly efficient metal‐free catalyst is developed by introducing F atoms into a 3D porous carbon framework (F‐doped carbon) toward N2 electroreduction. At −0.2 V versus reversible hydrogen electrode (RHE), the F‐doped carbon achieves the highest FE of 54.8% for NH3, which is 3.0 times as high as that (18.3%) of pristine carbon frameworks. Notably, at −0.3 V versus RHE, the yield rate of F‐doped carbon for NH3 reaches 197.7 µgNH3 mg−1cat. h−1. Such a value is more than one order of magnitude higher than those of other metal‐free electrocatalysts under the near‐ambient conditions for NH3 product to date. Mechanistic studies reveal that the improved performance in N2 electroreduction for F‐doped carbon originates from the enhanced binding strength of N2 and the facilitated dissociation of N2 into *N2H. F bonding to C atom creates a Lewis acid site due to the different electronegativity between the F and C atoms. As such, the repulsive interaction between the Lewis acid site and proton H suppresses the activity of H2 evolution reaction, thus enhancing the selectivity of N2 electroreduction into NH3.

The BiVO4 photoelectrochemical (PEC) electrode in tandem with a photovoltaic (PV) cell has shown great potential to become a compact and cost‐efficient device for solar hydrogen generation. However, the PEC part is still facing problems such as the poor charge transport efficiency owing to the drag of oxygen vacancy bound polarons. In the present work, to effectively suppress oxygen vacancy formation, a new route has been developed to synthesize BiVO4 photoanodes by using a highly oxidative two‐dimensional (2D) precursor, bismuth oxyiodate (BiOIO3), as an internal oxidant. With the reduced defects, namely the oxygen vacancies, the bound polarons were released, enabling a fast charge transport inside BiVO4 and doubling the performance in tandem devices based on the oxygen vacancy eliminated BiVO4. This work is a new avenue for elaborately designing the precursor and breaking the limitation of charge transport for highly efficient PEC‐PV solar fuel devices.

Electroreduction of N2 into NH3 represents a promising method for N2 fixation. However, due to the inertness of NN covalent triple bonds, this process remains a huge challenge to achieve a high yield rate of NH3. In this work, we designed an effective approach to promoting N2 activation by introducing oxygen vacancies into LaCoO3. In N2 electroreduction, LaCoO3 with oxygen vacancies (denoted as V o-LaCoO3) exhibited a Faradaic efficiency of 7.6% for NH3 at −0.6 V versus the reversible hydrogen electrode (RHE). Notably, at −0.7 V versus RHE, the yield rate for NH3 of V o-LaCoO3 reached 182.2 μgNH3 mg–1 cat. h–1, which was 2.8 times higher than that (65.3 μgNH3 mg–1 h–1) of pristine LaCoO3. To the best of our knowledge, the yield rate for NH3 of V o-LaCoO3 approaches the activities of the state-of-the-art catalysts toward N2 electroreduction. Density functional theory calculations revealed that enhanced activation of N2 over V o-LaCoO3 originated from the increased charge density around the valence band edge via the introduction of oxygen vacancies. Furthermore, the analysis of the thermodynamic limiting potentials for N2 reduction and H2 evolution demonstrated the higher selectivity for N2 electroreduction over V o-LaCoO3 relative to pristine LaCoO3.

Cu-based tandem nanocrystals have been widely applied to produce multicarbon (C 2+ ) products via enhancing CO intermediate (*CO) coverage toward CO 2 electroreduction. Nevertheless, it remains ambiguous to understand the intrinsic correlation between *CO coverage and C−C coupling. Herein, we constructed a tandem catalyst via coupling CoPc with the gas diffusion electrode of Cu (GDE of Cu−CoPc). A faradaic efficiency for C 2+ products of 82% was achieved over a GDE of Cu−CoPc at an applied current density of 480 mA cm −2 toward CO 2 electroreduction, which was 1.8 times as high as that over the GDE of Cu. Based on in situ experiments and density functional theory calculations, we revealed that the high *CO coverage induced by CO-generating CoPc promoted the local enrichment of *CO with the top adsorption mode, thus reducing the energy barrier for the formation of OCCO intermediate. This work provides an in-depth understanding of the surface coverage-dependent mode-specific C−C coupling mechanism toward CO 2 electroreduction.

The electrooxidation of propylene into propylene oxide under ambient conditions represents an attractive approach toward propylene oxide. However, this process suffers from a low yield rate over reported electrocatalysts. In this work, we develop an efficient electrocatalyst of Ag3PO4 for the electrooxidation of propylene into propylene oxide. The Ag3PO4 cubes with (100) facets exhibit the highest yield rate of 5.3 gPO m−2 h−1 at 2.4 V versus reversible hydrogen electrode, which is 1.6 and 2.5 times higher than those over Ag3PO4 rhombic dodecahedra with (110) facets and tetrahedra with (111) facets, respectively. The theoretical calculations reveal that the largest polarization of propylene on Ag3PO4 (100) facets is beneficial to break the symmetric π bonding and facilitate the formation of C-O bond. Meanwhile, Ag3PO4(100) facets exhibit the lowest adsorption energies of *C3H6 and *OH, inducing the lowest energy barrier of the rate-determining step and thus accounting for the highest catalytic performance.