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Upgrading CO2 into multi‐carbon (C2+) compounds through the CO2 reduction reaction (CO2RR) offers a practical approach to mitigate atmospheric CO2 while simultaneously producing high value chemicals. The reaction pathways for C2+ production involve multi‐step proton‐coupled electron transfer (PCET) and C−C coupling processes. By increasing the surface coverage of adsorbed protons (*Had) and *CO intermediates, the reaction kinetics of PCET and C−C coupling can be accelerated, thereby promoting C2+ production. However, *Had and *CO are competitively adsorbed intermediates on monocomponent catalysts, making it difficult to break the linear scaling relationship between the adsorption energies of the *Had/*CO intermediate. Recently, tandem catalysts consisting of multicomponents have been developed to improve the surface coverage of *Had or *CO by enhancing water dissociation or CO2‐to‐CO production on auxiliary sites. In this context, we provide a comprehensive overview of the design principles of tandem catalysts based on reaction pathways for C2+ products. Moreover, the development of cascade CO2RR catalytic systems that integrate CO2RR with downstream catalysis has expanded the range of potential CO2 upgrading products. Therefore, we also discuss recent advancements in cascade CO2RR catalytic systems, highlighting the challenges and perspectives in these systems. [ABSTRACT FROM AUTHOR]

Electrosynthesis of H2O2 has great potential for directly converting O2 into disinfectant, yet it is still a big challenge to develop effective electrocatalysts for medical‐level H2O2 production. Herein, we report the design and fabrication of electrocatalysts with biomimetic active centers, consisting of single atomic iron asymmetrically coordinated with both nitrogen and sulfur, dispersed on hierarchically porous carbon (FeSA‐NS/C). The newly‐developed FeSA‐NS/C catalyst exhibited a high catalytic activity and selectivity for oxygen reduction to produce H2O2 at a high current of 100 mA cm−2 with a record high H2O2 selectivity of 90 %. An accumulated H2O2 concentration of 5.8 wt.% is obtained for the electrocatalysis process, which is sufficient for medical disinfection. Combined theoretical calculations and experimental characterizations verified the rationally‐designed catalytic active center with the atomic Fe site stabilized by three‐coordinated nitrogen atoms and one‐sulfur atom (Fe‐N3S‐C). It was further found that the replacement of one N atom with S atom in the classical Fe‐N4‐C active center could induce an asymmetric charge distribution over N atoms surrounding the Fe reactive center to accelerate proton spillover for a rapid formation of the OOH* intermediate, thus speeding up the whole reaction kinetics of oxygen reduction for H2O2 electrosynthesis. [ABSTRACT FROM AUTHOR]

Unrestrained anthropogenic activities have severely disrupted the global natural nitrogen cycle, causing numerous energy and environmental issues. Electrocatalytic nitrogen transformation is a feasible and promising strategy for achieving a sustainable nitrogen economy. Synergistically combining multiple nitrogen reactions can realize efficient renewable energy storage and conversion, restore the global nitrogen balance, and remediate environmental crises. Here, we provide a unique aspect to discuss the intriguing nitrogen electrochemistry by linking three essential nitrogen‐containing compounds (i.e., N2, NH3, and NO3−) and integrating four essential electrochemical reactions, i.e., the nitrogen reduction reaction (N2RR), nitrogen oxidation reaction (N2OR), nitrate reduction reaction (NO3RR), and ammonia oxidation reaction (NH3OR). This minireview also summarizes the acquired knowledge of rational catalyst design and underlying reaction mechanisms for these interlinked nitrogen reactions. We further underscore the associated clean energy technologies and a sustainable nitrogen‐based economy. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of CO2 (CO2RR) to value‐added chemicals is of great significance for CO2 utilization, however the CO2RR process involving multi‐electron and proton transfer is greatly limited by poor selectivity and low yield. Herein, We have developed an atomically dispersed monovalent zinc catalyst anchored on nitrogenated carbon nanosheets (Zn/NC NSs). Benefiting from the unique coordination environment and atomic dispersion, the Zn/NC NSs exhibit a superior CO2RR performance, featuring a high current density up to 50 mA cm−2 with an outstanding CO Faradaic efficiency of ≈95 %. The center ZnI atom coordinated with three N atoms and one N atom that bridges over two adjacent graphitic edges (Zn‐N3+1) is identified as the catalytically active site. Experimental results reveal that the twisted Zn‐N3+1 structure accelerates CO2 activation and protonation in the rate‐determining step of *CO2 to *COOH, while theoretical calculations elucidate that atomically dispersed Zn‐N3+1 moieties decrease the potential barriers for intermediate COOH* formation, promoting the proton‐coupled CO2RR kinetics and boosting the overall catalytic performance. [ABSTRACT FROM AUTHOR]

Metal phthalocyanines (MePc) hold great promise in electrochemical reduction of CO2 to value‐added chemicals, whereas the catalytic activity of MePc‐containing polymers often suffers from a limited molecular modulation strategy. Herein, we synthesize an ultrathin conjugated microporous polymer sheath around carbon nanotubes by an ionothermal copolymerization of CoPc and H2Pc via the Scholl reaction. Given the H2Pc‐mediated regulation in the synthesis, CoII metal is well preserved in the form of single atoms on the polymer sheath of the carbon nanotubes. With the synergistic effect of H2Pc moieties as proton/electron donors, the composites can selectively reduce CO2 to CO with a high Faradaic efficiency (max. 97 % at −0.9 V) in broad potential windows, exceptional turnover frequency (97 592 h−1 at −0.65 V) and large current density (>200 mA cm−2). It is thus desirable to develop a family of heterogeneous polymerized MePc with molecularly regulating electrocatalytic activity. [ABSTRACT FROM AUTHOR]

Electrocatalysts play a key role in accelerating the sluggish electrochemical CO2 reduction (ECR) involving multi‐electron and proton transfer. We now develop a proton capture strategy by accelerating the water dissociation reaction catalyzed by transition‐metal nanoparticles (NPs) adjacent to atomically dispersed and nitrogen‐coordinated single nickel (Ni−Nx) active sites to accelerate proton transfer to the latter for boosting the intermediate protonation step, and thus the whole ECR process. Aberration‐corrected scanning transmission electron microscopy, X‐ray absorption spectroscopy, and calculations reveal that the Ni NPs accelerate the adsorbed H (Had) generation and transfer to the adjacent Ni−Nx sites for boosting the intermediate protonation and the overall ECR processes. This proton capture strategy is universal to design and prepare for various high‐performance catalysts for diverse electrochemical reactions even beyond ECR. [ABSTRACT FROM AUTHOR]

Regulating the local environment and structure of metal center coordinated by nitrogen ligands (M‐N4) to accelerate overall reaction dynamics of the electrochemical CO2 reduction reaction (CO2RR) has attracted extensive attention. Herein, we develop an axial traction strategy to optimize the electronic structure of the M‐N4 moiety and construct atomically dispersed nickel sites coordinated with four nitrogen atoms and one axial oxygen atom, which are embedded within the carbon matrix (Ni‐N4‐O/C). The Ni‐N4‐O/C electrocatalyst exhibited excellent CO2RR performance with a maximum CO Faradic efficiency (FE) close to 100 % at −0.9 V. The CO FE could be maintained above 90 % in a wide range of potential window from −0.5 to −1.1 V. The superior CO2RR activity is due to the Ni‐N4‐O active moiety composed of a Ni‐N4 site with an additional oxygen atom that induces an axial traction effect. [ABSTRACT FROM AUTHOR]

A new synthetic method to fabricate Ti3+-modified, highly stable TiO2 photoanodes for H2O oxidation is reported. With Ti foil as both the conducting substrate and the Ti3+/Ti4+ source, one-dimensional blue Ti3+/TiO2 crystals were grown by a one-step hydrothermal reaction. The concentration of Ti3+ was further tuned by N2H4 reduction, leading to a greater photoelectrocatalytic activity, as evidenced by a high photocurrent density of 0.64 mAcm-2 at 1.0 V vs RHE under simulated AM 1.5 G illumination. Electron paramagnetic resonance and Mott-Schottky plots reveal that higher charge-carrier density owing to N2H4 reduction contributes to the observed improvement. The generality of this synthesis method was demonstrated by its effectiveness in improving the performance of other types of photoanodes. By integrating the advantages of the 1D TiO2 architecture with those of Ti3+ self-doping, this work provides a versatile tool toward the fabrication of efficient TiO2 photoanodes. [ABSTRACT FROM AUTHOR]

Hitting water with nanotrees: A three‐dimensional branched heterojunction array for water oxidation based on cobalt‐doped α‐Fe2O3 nanorod cores and MgFe2O4 shells has been synthesized. Such an architecture not only has a large surface area and excellent light absorption properties, and shows fast charge transport, but also exhibits a very high photoelectrochemical activity for water oxidation and a high stability. [ABSTRACT FROM AUTHOR]