Yafei Li

Efficient O ₂ activation under mild conditions is central to oxidative biomass valorization, yet single‐atom catalysts often suffer from sluggish proton‐coupled oxygen intermediate conversion, particularly because of overly strong *OH adsorption. Inspired by the cooperative electron and proton management in cytochrome c oxidase, we report an α ‐MoC/Fe–N ₄ catalyst in which α ‐MoC nanoparticles are interfaced with Fe–N ₄ single‐atom sites on a nitrogen‐doped carbon scaffold. The α ‐MoC component plays a dual role: it withdraws electron density from Fe sites to weaken oxygen‐intermediate adsorption and promotes water dissociation to provide local protons for *OH‐to‐H ₂ O conversion. As a result, α ‐MoC/Fe–N ₄ exhibits a 2.8‐fold higher V _max for O ₂ activation than Fe–N ₄ and proceeds through a nearly four‐electron oxygen reduction pathway with negligible reactive oxygen species (ROS) generation. This interfacial strategy is generalizable to various M–N–C single‐atom catalysts, including Mn, Co, Ni, Cu, Sn, Ir, and Pt. Enabled by efficient O ₂ activation, α ‐MoC/Fe–N ₄ depolymerizes native birch lignin under mild alkaline conditions, substantially decreasing its molecular weight and cleaving β –O–4, β – β , and β –5 linkages. This work establishes an electron‐proton dual‐modulation strategy for constructing high‐performance single‐atom catalysts for biomass conversion.

Efficient O ₂ activation under mild conditions is central to oxidative biomass valorization, yet single‐atom catalysts often suffer from sluggish proton‐coupled oxygen intermediate conversion, particularly because of overly strong *OH adsorption. Inspired by the cooperative electron and proton management in cytochrome c oxidase, we report an α ‐MoC/Fe–N ₄ catalyst in which α ‐MoC nanoparticles are interfaced with Fe–N ₄ single‐atom sites on a nitrogen‐doped carbon scaffold. The α ‐MoC component plays a dual role: it withdraws electron density from Fe sites to weaken oxygen‐intermediate adsorption and promotes water dissociation to provide local protons for *OH‐to‐H ₂ O conversion. As a result, α ‐MoC/Fe–N ₄ exhibits a 2.8‐fold higher V _max for O ₂ activation than Fe–N ₄ and proceeds through a nearly four‐electron oxygen reduction pathway with negligible reactive oxygen species (ROS) generation. This interfacial strategy is generalizable to various M–N–C single‐atom catalysts, including Mn, Co, Ni, Cu, Sn, Ir, and Pt. Enabled by efficient O ₂ activation, α ‐MoC/Fe–N ₄ depolymerizes native birch lignin under mild alkaline conditions, substantially decreasing its molecular weight and cleaving β –O–4, β – β , and β –5 linkages. This work establishes an electron‐proton dual‐modulation strategy for constructing high‐performance single‐atom catalysts for biomass conversion.

We demonstrate that single-atom catalysts can be rationally engineered to couple the electrocatalytic oxygen reduction reaction with a catalase-like process, enabling a favorable H ₂ O ₂ to-O ₂ conversion pathway.

The intrinsic py-MnN ₄ centre of Mn–N–C single-atom catalysts is preferentially axially coordinated with an OH ligand and is immune to SCN ⁻ poisoning.

Photocatalytic hydrogen peroxide (H ₂ O ₂ ) synthesis via oxygen reduction reaction (ORR) offers a sustainable alternative to energy‐intensive anthraquinone processes. However, its efficiency is hindered by poor selectivity and instability stemming from reactive superoxide intermediates through the two‐step two‐electron (2e ⁻ ) route. Herein, inspired by the “induced‐fit” mechanism of enzymes, a strategy of self‐adaptive active sites modulation using flexible conjugated polymers engineered with nonplanar linking units was proposed. The flexible conjugated microporous polymers facilitated a transition of O ₂ adsorption from Pauling‐type to Yeager‐type. Among the designed polymers, CMP‐B4, which was constructed from 4,4′‐position‐coupled bipyridine units, exhibited optimal geometric matching capability for O ₂ activation. Specifically, upon the approach of O ₂ , the interaction between the lone‐pair electrons of nitrogen atoms in flexible bipyridine unit and π* orbitals of O ₂ induced a dihedral rotation (e.g., approximately 10° in CMP‐B4), playing a key role in promoting the one‐step 2e ⁻ ORR pathway, thus overcoming the limitations of poor adaptability to diverse O ₂ adsorption modes and restricted versatility of dual‐nitrogen units in the rigid nitrogen‐rich polymers. Such configuration of CMP‐B4 suppressed the formation of *OOH intermediates and achieved an excellent photocatalytic H ₂ O ₂ production rate of 6.21 mmol g ⁻¹ h ⁻¹ under continuous‐flow photocatalytic conditions over 24 h.

Photocatalytic hydrogen peroxide (H ₂ O ₂ ) synthesis via oxygen reduction reaction (ORR) offers a sustainable alternative to energy‐intensive anthraquinone processes. However, its efficiency is hindered by poor selectivity and instability stemming from reactive superoxide intermediates through the two‐step two‐electron (2e ⁻ ) route. Herein, inspired by the “induced‐fit” mechanism of enzymes, a strategy of self‐adaptive active sites modulation using flexible conjugated polymers engineered with nonplanar linking units was proposed. The flexible conjugated microporous polymers facilitated a transition of O ₂ adsorption from Pauling‐type to Yeager‐type. Among the designed polymers, CMP‐B4, which was constructed from 4,4′‐position‐coupled bipyridine units, exhibited optimal geometric matching capability for O ₂ activation. Specifically, upon the approach of O ₂ , the interaction between the lone‐pair electrons of nitrogen atoms in flexible bipyridine unit and π* orbitals of O ₂ induced a dihedral rotation (e.g., approximately 10° in CMP‐B4), playing a key role in promoting the one‐step 2e ⁻ ORR pathway, thus overcoming the limitations of poor adaptability to diverse O ₂ adsorption modes and restricted versatility of dual‐nitrogen units in the rigid nitrogen‐rich polymers. Such configuration of CMP‐B4 suppressed the formation of *OOH intermediates and achieved an excellent photocatalytic H ₂ O ₂ production rate of 6.21 mmol g ⁻¹ h ⁻¹ under continuous‐flow photocatalytic conditions over 24 h.

The electroreduction of nitrogen oxidative species emerges as a route for producing hydroxylamine (NH2OH). However, the mechanism governing its selective generation over the byproduct ammonia (NH3) is not well understood, impeding the rational design of high-performance catalysts. Here, we disclose a common phenomenon of cation-mediated interfacial microenvironment in promoting NO activation and NH2OH desorption kinetics, which is responsible for selective NH2OH electrosynthesis. Focusing on the established Co single-atom catalysts, our constant-potential modeling reveals that cations (e.g., K+) modulate the interfacial microenvironment and electronic structures, which not only facilitate the nonelectrochemical NH2OH desorption but also promote the rate-limiting hydrogenation of *NO to *NHO via the improved electron donation and back-donation. By contrast, such a K+-mediated interfacial environment is absent on Cu catalysts, where *NH2OH predominantly undergoes hydrogenation to NH3. This mechanism also rationalizes other typical NH2OH-producing catalysts, highlighting the cation effect and *NH2OH-based branching point. We further demonstrate the potential of axial coordination engineering for enhancing NH2OH production. This work advances the understanding of NH2OH electrosynthesis and provides practical guidance for catalyst design.

In this study, two different ferric hydroxyphosphate (FHP and FHP-B) catalysts, synthesized by the same procedure with or without the addition of aqueous ammonia have shown excellent performance in the hydrogenolysis of glycerol to 1,3-propanediol (1,3-PDO) (conversion of glycerol: 60.7%; selectivity of 1,3-PDO: 87.9%) and acetalization of glycerol to solketal (conversion of glycerol: 94.9%; solketal selectivity: 98.3%). Simultaneously converting glycerol to two high-value-added chemicals is of great significance. Meanwhile, the two catalysts are characterized by a series of instruments, and the results show that the addition of aqueous ammonia alters the concentration of Brønsted and Lewis acidic sites of the catalysts, thus allowing them to attack different hydroxyl groups on glycerol. The Brønsted acid sites (BAS) of the FHP catalyst without the addition of aqueous ammonia were more selective for the breaking of the 2°-OH bond, whereas the FHP-B catalyst, due to the presence of aqueous ammonia, converted some BAS to Lewis acid sites (LAS) during the synthesis process. A large amount of LAS was inclined to attack glycerol's 1°-OH bond, which is more favorable for the condensation reaction of glycerol and acetone. This finding innovatively provides a new strategy for the catalyst synthesis and a new perspective on reaction mechanism research.

Tandem carbon dioxide reduction reaction (CO ₂ RR) to multicarbon products (CO ₂ -CO-C ₂₊ ) such as ethylene represents a pivotal strategy for carbon valorization. However, conventional alkaline or neutral tandem systems limit the carbon dioxide utilization and stability due to severe (bi)carbonate formation. Here, we design a durable acidic-alkaline tandem system to efficiently synthesize C ₂₊ products, especially ethylene. In the acidic CO ₂ RR step, a catalyst with precisely controlled metal site distance was used to regulate *COOH adsorption. Typically, a 99.7 ± 0.4% carbon monoxide Faradaic efficiency (FE) at 1.4 amperes per square centimeter can be achieved using a catalyst with 0.5-nanometer nickel sites, surpassing the previously reported metal catalysts. When this catalyst was integrated into the acidic-alkaline tandem system and coupled with the alkaline carbon monoxide electroreduction, the ethylene and C ₂₊ FE reached 75.3 ± 1.2 and 92.5 ± 1.3% at 10 amperes, respectively, and remained stable for 400 hours. Our work provides solutions for the durable conversion of carbon dioxide to C ₂₊ products from catalyst and electrolyzer design.

Revealing vacancy-dopant synergistic effects in MoS ₂ for enhanced HER via DFT calculations and machine learning.