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Electrochemical CO2 reduction reaction (CO2RR) is crucial to addressing environmental crises and producing chemicals. Proton activation and transfer are essential in CO2RR. To date, few research reviews have focused on this process and its effect on catalytic performance. Recent studies have demonstrated ways to improve CO2RR by regulating proton transfer dynamics. This Concept highlights the use of regulating proton transfer dynamics to enhance CO2RR for the target product and discusses modulation strategies for proton transfer dynamics and operative mechanisms in typical systems, including single‐atom catalysts, molecular catalysts, metal heterointerfaces, and organic‐ligand modified metal catalysts. Characterization methods for proton transfer dynamics during CO2RR are also discussed, providing powerful tools for the hydrogen‐involving electrochemical study. This Concept offers new insights into the CO2RR mechanism and guides the design of efficient CO2RR systems. [ABSTRACT FROM AUTHOR]

Heteroatom‐doping in metal‐nitrogen‐carbon single‐atom catalysts (SACs) is considered a powerful strategy to promote the electrocatalytic CO2 reduction reaction (CO2RR), but the origin of enhanced catalytic activity is still elusive. Here, we disclose that sulfur doping induces an obvious proton‐feeding effect for CO2RR. The model SAC catalyst with sulfur doping in the second‐shell of FeN4 (Fe1−NSC) was verified by X‐ray absorption spectroscopy and aberration‐corrected scanning transmission electron microscopy. Fe1−NSC exhibits superior CO2RR performance compared to sulfur‐free FeN4 and most reported Fe‐based SACs, with a maximum CO Faradaic efficiency of 98.6 % and turnover frequency of 1197 h−1. Kinetic analysis and in situ characterizations confirm that sulfur doping accelerates H2O activation and feeds sufficient protons for promoting CO2 conversion to *COOH, which is also corroborated by the theoretical results. This work deepens the understanding of the CO2RR mechanism based on SAC catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni electron depletion on NiPc/CNTs is alleviated by doping electron-deficient B. • Ni site in NiPc/B-CNTs is electron-enriched state, lowering CO 2 RR reaction barrier. • The NiPc/B-CNTs presents prominent CO 2 RR performance in neutral electrolytes. Dispersed nickel phthalocyanine (NiPc) on carbon nanotubes (CNTs) is the promising electrocatalyst for carbon dioxide reduction (CO 2 RR), but the strong interfacial electron interaction causes Ni electron depletion, limiting CO 2 RR performance. Herein, engineering the heteroatom doping in CNTs is proposed to alleviate electron depletion of Ni sites toward effective CO 2 RR. Boron heteroatoms induce electron-enriched Ni sites in NiPc/B-CNTs compared to phosphorus, nitrogen, and fluorine doped catalysts, resulting in superior CO 2 RR performance. Impressively, the NiPc/B-CNTs presents high CO Faraday efficiency (FE CO) of >98 % from −20 to −80 mA cm−2 and excellent stability up to 37 h with sustained FE CO of > 90 % in neutral electrolyte. Theoretical and experimental investigation reveals that implanting B heteroatoms alleviates Ni electron depletion via weakening electron transfer from NiPc to CNTs and thus reduces reaction barrier of *COOH formation, facilitating CO 2 RR. This study highlights importance of modifying carbon substrate in development of supported molecular catalysts for practical applications. [ABSTRACT FROM AUTHOR]

Ruthenium (Ru)‐based catalysts, with considerable performance and desirable cost, are becoming highly interesting candidates to replace platinum (Pt) in the alkaline hydrogen evolution reaction (HER). The hydrogen binding at Ru sites (Ru−H) is an important factor limiting the HER activity. Herein, density functional theory (DFT) simulations show that the essence of Ru−H binding energy is the strong interaction between the 4dz2 orbital of Ru and the 1s orbital of H. The charge transfer between Ru sites and substrates (Co and Ni) causes the appropriate downward shift of the 4dz2 ‐band center of Ru, which results in a Gibbs free energy of 0.022 eV for H* in the RuCo system, much lower than the 0.133 eV in the pure Ru system. This theoretical prediction has been experimentally confirmed using RuCo alloy‐nanosheets (RuCo ANSs). They were prepared via a fast co‐precipitation method followed with a mild electrochemical reduction. Structure characterizations reveal that the Ru atoms are embedded into the Co substrate as isolated active sites with a planar symmetric and Z‐direction asymmetric coordination structure, obtaining an optimal 4dz2 modulated electronic structure. Hydrogen sensor and temperature program desorption (TPD) tests demonstrate the enhanced Ru−H interactions in RuCo ANSs compared to those in pure Ru nanoparticles. As a result, the RuCo ANSs reach an ultra‐low overpotential of 10 mV at 10 mA cm−2 and a Tafel slope of 20.6 mV dec−1 in 1 M KOH, outperforming that of the commercial Pt/C. This holistic work provides a new insight to promote alkaline HER by optimizing the metal‐H binding energy of active sites. [ABSTRACT FROM AUTHOR]

Atomically dispersed transition metal sites have been extensively studied for CO2 electroreduction reaction (CO2RR) to CO due to their robust CO2 activation ability. However, the strong hybridization between directionally localized d orbits and CO vastly limits CO desorption and thus the activities of atomically dispersed transition metal sites. In contrast, s‐block metal sites possess nondirectionally delocalized 3s orbits and hence weak CO adsorption ability, providing a promising way to solve the suffered CO desorption issue. Herein, we constructed atomically dispersed magnesium atoms embedded in graphitic carbon nitride (Mg‐C3N4) through a facile heat treatment for CO2RR. Theoretical calculations show that the CO desorption on Mg sites is easier than that on Fe and Co sites. This theoretical prediction is demonstrated by experimental CO temperature program desorption and in situ attenuated total reflection infrared spectroscopy. As a result, Mg‐C3N4 exhibits a high turnover frequency of ≈18 000 per hour in H‐cell and a large current density of −300 mA cm−2 in flow cell, under a high CO Faradaic efficiency ≥90 % in KHCO3 electrolyte. This work sheds a new light on s‐block metal sites for efficient CO2RR to CO. [ABSTRACT FROM AUTHOR]

[Display omitted] • An electro-production and detection of H 2 O 2 system is constructed by Ni-SAC. • In-situ electro-detection of H 2 O 2 is more reliable than spectrophotometry. • The sensor displays a low detection limit of 6.87 pM towards H 2 O 2 detection. • NiOOH on single Ni site is an intermediate for H 2 O 2 detection in alkaline medium. Electrochemical oxygen reduction reaction (ORR) to hydrogen peroxide (H 2 O 2) is a common method to address the growing demands of H 2 O 2. To map a clear understanding of structure–activity relationship of electrocatalyst for H 2 O 2 production, it is necessary to real-time quantitative monitor of H 2 O 2 in the initial production process. However, we found that the common off-line methods such as spectrophotometry, titration, etc., are not reliably during in-situ ORR process. Here, a simple and real-time simultaneous electrochemical production and determination of H 2 O 2 system is constructed by using a dual-functional nickel (Ni) single-atom electrocatalyst. The electro-production part is conducted with a DC power supply, air pump, and dual-electrode system, while the electro-detection part consists of a three-electrode system. Compared with traditional off-line H 2 O 2 measure methods, the present on-line determination of H 2 O 2 protocol provides more reliable results in the quantitative monitoring of H 2 O 2 , and with a wide detection concentration range from 20 pM to 22.2 mM and a low detection limit of 6.87 pM. NiOOH on single Ni site is an important intermediate for efficient detection of H 2 O 2 in alkaline medium. The Ni-SAC sensor also shows well anti-interferential and selective ability, high reproducibility and stability of H 2 O 2 sensing up to 12 days. This simple-to-operate method offers a new window to record a reliable structure–activity relationship on electrocatalyst engineering in electrochemistry. [ABSTRACT FROM AUTHOR]