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[Display omitted] • The unique Pt-O-Cu structure is constructed on the 2.5Pt-2Cu/Fe 2 O 3 catalyst. • The Pt-O-Cu site shows the best reactivity for EWGS reaction. • The Pt-O-Cu site balances the binding ability of CO and the activation of OH–. • The Pt-O-Cu structure greatly boots the capability in antioxidation of Pt. Electrochemical water–gas shift (EWGS) reaction is an emerging technology with energy-saving and environmental-friendly advantages to produce high-purity hydrogen form the waste gas containing CO. However, it remains a significant challenge to design superior activity and highly durable EWGS electrocatalysts, particularly with low content of noble metals. Herein, a series of Pt-xCu/Fe 2 O 3 (x = 0, 2, 5) catalysts are synthesized by the complexation precipitation method to construct coupling sites between Pt and CuOx, aiming to optimize the adsorption of CO and the activation of OH–. The obtained 2.5Pt-2Cu/Fe 2 O 3 catalyst presents a unique Pt-O-Cu structure, delivering a much lowest onset potential, high specific activity, and excellent mass activity (1.5 A·mg Pt -1) at 0.73 V (vs. RHE), which is over 15 and 3 times that of commercial Pt/C (20%) and unmodified Pt/Fe 2 O 3 catalyst, respectively. Meanwhile, the in-situ X-ray absorption results demonstrate that the facilitated interaction among the Pt-O-Cu structure promotes the high durability of the 2.5Pt-2Cu/Fe 2 O 3 catalyst and the operability at high potential. More importantly, the moderate binding of CO and moderate activation of OH* are suggested for boosting the reactivity in the CO electro-oxidation reaction. In particular, the fabricated Pt||2.5Pt-2Cu/Fe 2 O 3 , employed in coupling the HER and CO electro-oxide reaction, shows a remarkable hydrogen production of about 98 mmol H2 ·h−1·mg Pt −1 at 0.8 V (vs. RHE). This work also definitely confirms the possibility of the catalyst being applied to produce hydrogen under practical conditions with different concentrations of CO, even being applied in the purification of trace CO in a hydrogen-rich atmosphere. [ABSTRACT FROM AUTHOR]

A strategy for one-pot asymmetric β-C-H functionalization of aldehydes under O 2 has been proposed, catalysed by the hydroxide-layered Fe(III) sites synergistic with confined interlayer amines through a cascade oxidation-addition process. [Display omitted] • First proposal of a heterogeneous strategy to boost the one-pot asymmetric β-C-H functionalization of aldehyde under O 2 using hydroxide-layered Fe(III) sites synergistic with confined interlayer amine. • Achievements of an excellent regioselectivity (>99%), a good stereoselectivity (90%), and a moderate yield (65%) for the major β-functionalized diastereomer. • Good reusability of the L-proline intercalated Fe(III)-containing LDHs in the heterogeneous catalysis. Asymmetric functionalization of inert β-C-H is one of the most powerful strategies in organic synthesis, but of great challenge in the efficient β-C-H activation and the enantioselective C-heteroatom formation. Here, this work proposes an elegant strategy for one-pot asymmetric β-C-H functionalization of aldehyde under O 2 catalyzed by hydroxide-layered Fe(III) sites synergistic with confined interlayer amine through a cascade oxidation-addition process on L-proline intercalated Fe-containing layered double hydroxides (LDHs), in which the direct β-H elimination of aldehyde on hydroxide-layered Fe(III) sites with the two-electron abstraction promoted by the Fe(III):N coordination as the key step to efficiently oxidize the enamine. The major β-functionalized diastereomer in the asymmetric nitromethylation of 3-phenylpropanal has been afforded in a regioselectivity of up to >99%, a stereoselectivity of 90%, and a yield of 65% on L-proline intercalated Mg 3.00 Al 0.47 Fe 0.45 -LDHs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel strategy on targeted activation of alcoholic sp 3 C α -H bonds by synergistic H-bonding protection of O–H bonds is put forward. • Atomic Fe-N sites with the uncoordinated N species presents a synergistic adsorption of ethanol O–H bonds, providing the O–H protection by H bonding. • Targeted generation and excellent stabilization of •CH(OH)R radicals under ambient temperature are achieved. • Direct C–C construction of generated •CH(OH)R radicals with a variety of N -heterocycles contributes to an efficient Minisci hydroxyalkylation in a yield of 64 ∼ 98 %. The direct sp 3 C–H functionalization of alcohol with N -heterocycles is the most atom-economical pathway to produce hydroxyalkylated N -heterocycles. However, the targeted C–H activation to enable the direct C–C coupling still remains of great challenge due to the concomitant activation of alcoholic O–H. This work puts forward a H-bonding protection for alcoholic O–H for the targeted activation of alcoholic C α -H bonds. Atomic Fe-N sites anchored in graphitic carbon nitride with uncoordinated nitrogen sites has thus been proposed for this strategy, in which atomic Fe(II)-N sites are supposed to be responsible for the targeted activation of alcoholic C α -H and the surface uncoordinated nitrogen to for the H-bonding with alcoholic O–H. To demonstrate the strategy, the precise modulation on the atomic Fe-N coordination in the 6-fold cavity from three heptazines have been elaborated. Atomic Fe with four N atoms from two heptazines assisted with the uncoordinated N from the free one heptazine has presented a synergistic H-bonding protection of alcoholic O–H bonds. As a result, the targeted generation and excellent stabilization of hydroxyethyl radicals have been achieved under ambient temperature. The strategy has been successfully applied for 1-propanol, 2-propanol, 1-butanol, and 1-pentanol, thus achieving efficient C–C formation in the hydroxyalkylation of varied N -heterocycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • A class of Ru-Co single-atom alloy catalysts (marked as Ru x Co 1 SAA, x stands for Ru/Co molar ratio) were prepared. • The electronic structure of Ru x Co 1 SAA could be effectively tuned by regulating the Ru/Co molar ratio. • A moderate ratio of Ru/Co (1.7:1) favors superior NH 3 synthesis rate. • The excess Ru destroys the SAA structure, resulting in the diminution of SAA advantages. Rational design of efficient catalysts for ammonia (NH 3) synthesis at mild conditions is of paramount importance for the development of electrolysis driven Haber-Bosch (e HB) process. Ammonia synthesis is a structure sensitive reaction, and any small change of electronic structure could result in dramatic change of catalytic activity, especially for the Ru-based NH 3 synthesis catalysts. Electronic structure modulation of the Ru-based catalysts could provide desirable catalytic activity. Herein, we explore a class of Ru-Co single-atom alloy catalysts (marked as Ru x Co 1 SAA, x stands for Ru/Co molar ratio), in which Co single atoms are located on Ru nanoclusters to form Co-Ru coordination, and then electronic structure of Ru x Co 1 SAA could be effectively tuned by regulating the Ru/Co molar ratio. Our studies show that a moderate ratio of Ru/Co (1.7:1) favors superior NH 3 synthesis rate and low activation energy. Using a suite of elaborate characterizations, we have observed that the outstanding performance over Ru 1.7 Co 1 SAA can be attributed to the electron redistribution between Ru and Co atom, resulting in an upshift of d band center and lowering of work function. However, there is decrease of NH 3 synthesis rate when Ru/Co molar ratio is 2, due to the partial detachment of Ru entities from SAA structure, and the formed individual Ru nanoparticles (NPs) overlay the surface of catalyst. In such a case, N 2 activation behavior over Ru 2 Co 1 is alike that of Ru NPs catalysts. The present study demonstrates that the Ru/Co ratio in SAA structure can effectively regulate the electronic structure of catalyst for NH 3 synthesis rate enhancement. [ABSTRACT FROM AUTHOR]

The decrease of Ru particle size from nanoparticles (NPs) to nanoclusters (NCs) can not only increase the NH 3 synthesis performance, but also increase the proportion of corner sites. [Display omitted] • A series of diverse Ru particle sizes (1.4–5.0 nm) over N-doped carbon support were successfully prepared by colloidal Ru deposition method. • The decrease of Ru particle size from nanoparticles (NPs) to nanoclusters (NCs) can not only increase the NH 3 synthesis performance, but also promote the activation of N 2 via an association pathway. • The ample corner sites over Ru NCs can decrease the work function and thus promote N 2 activation. Ammonia (NH 3) synthesis is a structure-sensitive reaction, where a minute variation of catalyst structure would lead to a dramatic change of activity. To date, the roles of Ru size on NH 3 synthesis still remain elusive, and it remains a major challenge. Herein, a series of Ru catalysts with sizes ranging from 1.4 to 5.0 nm were prepared by colloidal Ru deposition, which allows the investigation of size influence on NH 3 synthesis. Through analyses of the geometric and electronic properties of variable-sized Ru particles, it shows that the reduction of Ru particle size could increase the proportion of corner sites while decrease that of terrace sites, which can decrease the work function and thus promote N 2 for its activation. Isotopic investigations show that the decrease of dissociative contribution but the increase of associative contribution as Ru particle size was decreased from 5.0 to 1.4 nm. Meanwhile, the NH 3 synthesis rate increases when the size of Ru catalysts decreases from 5.0 to 1.4 nm. Using a suite of elaborate characterizations, we have observed that 1.4 nm Ru nanoclusters (NCs) with ample corner sites are conducive to activate N 2 via an associative route. As a result, the 1.4 nm Ru NCs catalyst shows the highest NH 3 synthesis rate (up to 17.13 mmol NH3 g cat −1h−1) at 400 ℃ and 1 MPa. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rux/BaCeO 3 catalysts with different Ru particle sizes were accurately synthesized. • NH 3 synthesis rate increases obviously with the decrease of Ru particle size. • The reduction of Ru size promotes the generation of more Ce3+ and O v species. • The electron donation from Ce3+ and O v to Ru centers promotes N 2 dissociation. • The enhanced hydrogen spillover on small Ru size decreases hydrogen poisoning. Identifying optimal Ru size in NH 3 synthesis can improve reaction activity and maximize the utilization of Ru to reduce catalyst cost. However, previous researches are focused on large Ru particle size (≥2 nm) while that below 2 nm in NH 3 synthesis is unclear. Here we synthesized a series of Ru x /BaCeO 3 with different Ru sizes (x = 1.1–3.0 nm) through size-controlled Ru colloid. With the decrease of Ru size, NH 3 synthesis rate over Ru1.1/BaCeO 3 increases to 19.4 mmol g cat −1h−1 at 400 °C and 1 MPa, which is 5.7 times that of Ru3.0/BaCeO 3 and superior to most of Ru-based catalysts previously reported. It reveals that the reduction of Ru size enhances the generation of Ce3+ and oxygen vacancies in BaCeO 3 , which can donate electron to Ru centers and promote N 2 dissociation. Moreover, the small Ru size enhances hydrogen spillover from Ru to BaCeO 3 to alleviate hydrogen poisoning, resulting in efficient NH 3 synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • M single atom (M = Fe, Co, Ni) anchored on Ru nanoclusters were prepared to form M 1 Ru SAA. • Co 1 Ru SAA shows the highest NH 3 synthesis rate and TOF Ru value. • Compared with Co-Ru nanoparticle alloy, Co 1 Ru SAA exhibits lower work function and up-shift d band center. • SAA structure effectively tune N 2 activation pathway. The desire of green ammonia (NH 3) production requires efficient catalysts that could operate at mild conditions. However, the activity of catalysts is restricted by scaling relation that low activation energy of N 2 is in conjunction with the over-strong affinity of intermediates, which blocks adsorption sites of catalyst and hinders NH 3 production. Single atom alloy (SAA) is an efficient approach to circumvent this relation. In the present work, we offer a feasible strategy of preparing M 1 Ru (M = Fe, Co, Ni) SAA. Our studies show that Co 1 Ru SAA has the highest NH 3 synthesis rate and the largest TOF Ru value among M 1 Ru SAA. Compared with CoRu nanoparticle alloy (NPA), Co 1 Ru SAA has stronger electronic interaction between Co and Ru, which induces lower work function and up-shift d band center toward Fermi level for Co 1 Ru SAA, thus promoting N 2 activation. Meanwhile, the unique SAA structure could effectively tune N 2 activation pathway. Those findings make a contribution to the development of advanced catalysts for efficient NH 3 synthesis at mild conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Unique pompon-like RuCo catalysts were fabricated. • Atomically dispersed Ru-Co sites facilitated the adsorption/activation of reactants. • Excellent catalytic performance was achieved in the guaiacol hydrodeoxygenation. • Ru-Co synergy, as well as favorable hcp structure, contributed to high catalytic efficiency. Currently, the highly efficient conversion of biomass resources into highly valuable chemicals and biofuels is one of the most prospective approaches to reduce greenhouse gases emission and environmental pollution caused by excess consumption of fossil fuels. Herein, three-dimensional pompon-like well-defined RuCo particles with tunable crystallographic structures and surface atomically dispersed Ru atoms were constructed and intensively investigated as support-free metal catalysts in the hydrodeoxygenation (HDO) of lignin-derived guaiacol. It was demonstrated that the 300 °C-reduced RuCo sample possessed the hexagonal close-packed (hcp) crystallographic structure with surface abundant atomically dispersed Ru atoms, whereas 600 °C-reduced RuCo sample presented the face-centered cubic phase with lower surface Ru concentration. The as-fabricated RuCo-300 sample showed excellent catalytic HDO activity with a high cyclohexane yield of 85.3%. Comprehensive structural characterizations unveiled that the introduction of atomically dispersed Ru atoms into the RuCo-300 favored the formation of abundant surface Ru-Co sites, as well as electron-rich Ru0, and such-constructed Ru-Co sites were highly beneficial to the hydrogen dissociation on single Ru0 atoms and the further hydrogen spillover to adjacent Co0 atoms to promote the HDO process. Moreover, density functional theory (DFT) calculations revealed that the hcp structure of RuCo catalysts benefited the adsorption of guaiacol. The unique pompon-like microstructure of RuCo catalysts was conducive to the exposure of active sites and provided more open channels for the easy diffusion of reactants and products. Over the RuCo-300 catalyst, the guaiacol HDO could proceed rapidly via an initial demethoxylation reaction. The present Ru-Co synergetic catalysis in the structure of RuCo catalysts would provide a new strategy for constructing robust heterogeneous bimetal catalysts applied in practical HDO processes of a variety of lignin-derived phenolic compounds. [ABSTRACT FROM AUTHOR]

• A dynamic N- and H-involved cyclic reaction pathway proposed for NH 3 production. • A dual-path mechanism including chemical looping and thermal catalysis illustrated. • Bottleneck of direct N N dissociation bypassed. The synthesis of ammonia via the Haber-Bosch process using Fe-derived catalysts requires harsh reaction conditions. It is hence meaningful to develop catalysts for low-temperature synthesis of ammonia for industrial application. Herein for the first time, we report that with the synergy between LaN and Ru/ZrH 2 , NH 3 can be synthesized via a dual-path mechanism. The LaN-promoted Ru/ZrH 2 catalyst shows exceptionally high NH 3 synthesis rate (up to 305 mmol NH3 g Ru −1 h−1) at 350 °C under 1 MPa and remarkable durability (tested for 200 h). The outcomes of isothermal surface reaction and a suite of 15N 2 and D 2 isotopic labeling experiments reveal that the N3− of LaN reacts with H− ions to produce NH 3 , leaving behind N and H vacancies. The initial state of Ru/xLaN/ZrH 2 can be restored by having the N and H entities replenished under the atmosphere adopted for NH 3 synthesis. Moreover, based on the results of N 2 reaction order, nitrogen K-edge NEXAFS, in situ XPS as well as in situ DRIFTS analyses under a 25%N 2 -75%D 2 atmosphere, it is reckoned that the direct dissociation of N 2 does not occur on the LaN-promoted Ru/ZrH 2 catalyst while N 2 hydrogenation takes place via an associative pathway under mild conditions. For the hydrogenation of N 2 , an appropriate amount of LaN would induce a synergic effect on the Ru active sites, leading to facile activation and hydrogenation of N 2 to *N 2 H 2. Nonetheless, an excess amount of LaN would result in blocking of Ru sites, consequently hindering the formation of *N 2 H 2 and decreasing the catalytic activity. Following the associative and chemical looping pathways, the LaN-promoted Ru/ZrH 2 catalyst bypasses the bottleneck of N 2 direct dissociation, making the synthesis of NH 3 at mild conditions possible. [ABSTRACT FROM AUTHOR]

• Mo 2 C/CFP-Act is prepared via continuous cathode polarization technique. • Mo 2 C/CFP-Act is an excellent electrocatalyst for the hydrogen evolution reaction. • Mechanism study unveils the Pt single atom intrinsic role in Mo 2 C/CFP catalysts. Dispersing catalytically active metals as single atoms on supports offer an efficient pathway to minimize amount of precious metals. Although platinum (Pt) is highly active for HER, it is highly desirable to find ways to improve the HER performance and also keeping them stable during catalytic reactions while minimizing the Pt loading. Herein, we report a cathode polarization technique to disperse isolated single Pt atoms on β-Mo 2 C as a catalyst for HER. The isolated Pt atoms partially occupy Mo sites in Mo 2 C lattice by forming Pt-Mo shells, which maximize the utilization ratio of platinum noble metals. The single atoms catalyst Mo 2 C/CFP-Act even exhibited 1.9 and 1.1 times higher current density (@ potential of 0.4 V vs. RHE) than that of Pt NPs catalysts (Mo 2 C/CFP-Pt) after mass normalization in both acidic and alkali solution. Furthermore, DFT calculations demonstrate that Mo 2 C/CFP-Act exhibits favorable ΔG H* for the adsorption and desorption of hydrogen. The high HER activity of the Mo 2 C/CFP-Act catalyst is related to the Mo-Pt center located in Mo 2 C matrix, where the electronic structure of the Mo-Pt centers more efficient in donating electron to the σ* antiorbital of the H 3 O+ molecule. This study sheds new light on the HER catalysis mechanism of isolated metal atoms based on fundamental understanding in molecular governing factors. [ABSTRACT FROM AUTHOR]