Efficient and controllable hydrogen activation through heterogeneous catalysis is crucial for producing clean energy and chemicals. However, the fragile nature of hydrogen species and the complexity of material surfaces make it challenging to precisely identify critical intermediate species, as well as their atom-scale conformations and locations. This necessitates the development of high-resolution in situ characterization techniques for accurate hydrogen detection.Solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for analyzing surface species on heterogeneous catalysts, providing atomic-level structural information. However, conventional MAS NMR, which detects species remaining on solid catalysts after they have been separated from their reaction environment, is incapable of capturing volatile intermediates like activated hydrogen species.Recently, a research team led by Prof. HOU Guangjin from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has revealed an environment-sensitive nondissociative activated dihydrogen binding on the reduced ceria surface, closely resembling dihydrogen complexes in molecular science, using state-of-the-art high-pressure operando solid-state NMR. The study was published in Journal of the American Chemical Society.Revealing the nondissociative activated dihydrogen binding on reduced ceria surface by high-pressure operando solid-state NMR spectroscopy (Image by YAO Xinlong and JI Yi)The researchers fully utilized the high-pressure operando solid-state NMR technique, alongside a comprehensive set of H2/D2/HD adsorption experiments and various NMR spectroscopic methods, to investigate the states of activated hydrogen species on ceria surfaces.The researchers found that the hydrogen species bound to the reduced ceria surfaces were primarily nondissociated dihydrogen species, resembling the dihydrogen complexes in homogeneous and enzymatic catalysis. They identified these nondissociated dihydrogen species as retaining their hydrogen-hydrogen bonds on the ceria surface. Additionally, they demonstrated that these species exhibited slightly reduced J-coupling and longer T1 relaxation times compared to gaseous molecules, confirming bond length stretching, reduced mobility, and their bound and activated nature.Furthermore, the researchers and their collaborators showed that these bound dihydrogen species were confined by surface oxygen vacancies. Importantly, the proton isotropic chemical shifts were found to correlate with the degree of surface reduction, providing a high-resolution, nondestructive method for quantitatively analyzing the structure and catalytic functions of different catalyst surfaces."On one hand, our study bridges the gap between homogeneous organometallic catalysis and heterogeneous catalysis, offering valuable insights into the hydrogenation mechanism and potentially enhancing hydrogen utilization," said Prof. HOU."On the other hand, the analytic approach presented here can be applied to analyze the adsorption and activation processes of many other volatile molecules, such as CH4, CO, and CO2, benefiting the rational design of more efficient catalysts."The above work was financially supported by the National Key R&D Program of China, the National Natural Science Foundation of China, and the DICP Innovation Foundation.

Molybdenum (Mo) carbides, known for their unique electronic and structural properties, are considered promising alternatives to noble metal catalysts in heterogeneous catalysis. However, traditional methods for preparing Mo carbides suffer from complex processes, stringent synthesis conditions, challenging crystal regulation, and high energy consumption. Additionally, Mo carbides are susceptible to oxidation and deactivation, which poses a significant barrier to their widespread application.Recently, a research group led by Prof. SUN Jian from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) developed a facile strategy to establish Mo carbide catalysts for efficient CO2 conversion, bypassing the complicated carburization process of traditional methods. This study was published in Nature Chemistry.Reaction-induced carburization on metastable Mo oxides made by the FSP method (Image by YU Jiafeng)The researchers fabricated an Ir-modified MoO3 catalyst using a one-step flame spray pyrolysis (FSP) method, resulting in metastable Mo oxide species due to the rapid quenching from high temperatures. This unique structure facilitated reaction-induced carburization during the RWGS reaction, thus creating oxidation-resistant Mo oxycarbide (MoOxCy) active sites.The catalyst exhibited excellent activity and stability, highlighting the superiority of reaction-induced Mo carbide catalysts. At 600°C, it achieved a CO production rate of 17.5 molgcat-1 h-1 with 100% CO selectivity. No significant deactivation was observed over a 2,000-hour stability test, showing its great potential for industrial applications.Further investigation revealed that the crucial active sites in the RWGS reaction were the unsaturated MoOxCy species on the surface of Mo carbides. These species could maintain a dynamic equilibrium in the combined reduction, carburization, and oxidation atmosphere, preventing severe deactivation.Additionally, the researchers proposed a new carbon cycle pathway in the RWGS reaction that was more thermodynamically favorable than the traditional redox pathway by promoting the H2 dissociation through *COH species. This pathway could act as a supplement to the redox mechanism, enhancing CO2 conversion on Mo carbides and leading to superior catalytic performance."Our study provides a low energy-consuming strategy for developing Mo carbides as efficient catalysts and paves the way for the application of a low-cost Mo-based catalyst system for CO2 utilization," said Prof. SUN.

β-Farnesene is widely used in the production of polymers, surfactants, and lubricants, and it also serves as a suitable jet fuel substitute. Microbial biosynthesis offers a sustainable way to produce β-farnesene from renewable feedstocks. Methanol, an ideal feedstock for bio-manufacturing, can be produced in large quantities from CO2 through green energy like solar energy.Recently, a research group led by Prof. ZHOU Yongjin from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) engineered and optimized Ogataea polymorpha for bioproduction of β-farnesene from sole methanol. The study was published in Metabolic Engineering.The researchers systematically engineered O. polymorpha by using multiple engineering strategies to create strains optimized for efficient β-farnesene production. They used a fatty acid overproducing strain as the chassis for β-farnesene biosynthesis, as it had already been extensively modified for efficient acetyl-CoA and NADPH supply and adaptively evolved for methanol tolerance. By further optimizing the MVA pathway and engineering acetyl-CoA supply, they achieved a β-farnesene production of 14.7 g/L in a 5-L fed-batch bioreactor.

Hydroformylation, a key homogeneous reaction known for its atom economy, is a crucial industrial process for converting alkenes and syngas to aldehydes. These aldehydes can be used in the production of alcohols, amines, carboxylic acids, and other high-value-added fine chemicals. Currently, the annual production of aldehydes and their subsequent hydrogenated alcohols through hydroformylation exceeds 25 million tons.A research group led by Prof. YAN Li and Prof. DING Yunjie from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Science (CAS) developed a highly active and stable porous organic polymer supported single rhodium site (Rh-POPs) catalyst. This catalyst was applied to heterogeneous ethylene hydroformylation, addressing the challenges of precious metal and phosphorus ligand loss in traditional homogeneous technologies.In August 2020, the world's first demonstration of heterogeneous ethylene hydroformylation and subsequent hydrogenation to produce n-propanol (50000 t/year) using the Rh-POPs catalysts was completed in Zhejiang Province, China. The plant has been operating steadily for the past four years.Recently, this group further investigated and revealed the dynamic mechanism of tunable regioselectivity in propylene hydroformylation. Their study was published in Nature Communications.Schemes to map the active center and the dynamic evolution of hemilabile coordination (Image by FAN Benhan)The researchers studied the precise structure of the active centers in industrially applied Rh-POPs catalysts and their dynamic evolution under real reaction conditions. They found that during the hydroformylation, the adsorption, activation, reaction, and desorption of guest molecules on the Rh-P coordination active centers were accompanied by the dissociation and re-coordination of Rh-P hemilabile-coordination bonds. This process enabled the Rh-P active centers to dynamically shift between "open" and "closed" coordination states, forming different steric hindrances that regulated the regioselectivity of the aldehyde product.“These state-of-the-art techniques and multiscale analysis help us to understand how the hemilabile effect in heterogeneous catalysis influences the electronic state and geometric configuration of metal active centers, further affecting the catalyst's activity and regioselectivity,” said Prof. YAN“It provides novel insights for the rational design of hydroformylation catalysts with tunable regioselectivity for future industrial applications,” said Prof. DING.

Organic redox-active molecules (ORAMs) are abundant and diverse, offering significant potential for cost-effective and sustainable energy storage, particularly in aqueous organic flow batteries (AOFBs). However, ensuring the stability of the ORAMs during the charge and discharge process is critical, as side reactions can deactivate them and eliminate their redox activity. Air stability remains a challenge for many ORAMs, complicating their practical use.Recently, a research group led by Prof. LI Xianfeng and Prof. ZHANG Changkun from the Dalian Institute of Chemical Physics (DlCP) of the Chinese Academy of Sciences (CAS) developed novel naphthalene derivatives with active hydroxyls and dimethylamine scaffolds that were stable in air and served as effective catholytes for AOFBs. This study, published in Nature Sustainability, demonstrates that these novel ORAMs can achieve long-term stable cycling even under air-atmosphere conditions.Chemical and electrochemical reaction of the naphthalene derivatives (Image by ZHAO Ziming and ZHANG Changkun)ORAMs are challenged with instability and high cost, particularly when used without inert gas protection. This can lead to irreversible capacity loss and a reduced battery lifespan.In this study, the researchers synthesized active naphthalene derivatives using a scalable approach that combined chemical and in situ electrochemical methods. This approach simplified the purification process and significantly reduced the cost of molecular synthesis.Moreover, the researchers demonstrated specific structure changes in the naphthalene derivatives during the electrochemical process. The as-prepared naphthalene derivatives featured a multisubstituted framework with hydrophilic alkylamine scaffolds, which not only protected against potential side reactions but also improved their solubility in aqueous electrolytes.The 1.5 mol/L naphthalene-based AOFB displayed stable cycling performance for 850 cycles (about 40 days) with a capacity of 50 Ah/L. Remarkably, even with continuous air flow in the catholyte, the naphthalene-based AOFB could run smoothly for approximately 600 cycles (about 22 days) without capacity and efficiency decay. This demonstrated that the naphthalene-based catholyte had excellent air stability.Apilot-scale naphthalene-based flow stack (Image by ZHAO Ziming and ZHANG Changkun)Furthermore, the researchers scaled up the preparation of naphthalene derivatives to the kilogram scale (5 kg per pot). Pilot-scale battery stacks containing these naphthalene derivatives achieved an average system capacity of approximately 330 Ah. They exhibited remarkable cycling stability over 270 cycles (about 27 days), with a capacity retention of 99.95% per cycle."This study is expected to open a new field in the design of air-stable molecular for sustainable and air-stable electrochemical energy storage," said Prof. LI.

The synthesis of molybdenum carbide catalysts typically requires high temperature, leading to inevitable passivation in an oxygen-containing atmosphere. Developing a new route to produce molybdenum carbide at low temperatures is challenging but essential to increase the density of surface active sites.Recently, a research group led by Prof. BAO Xinhe and Prof. FU Qiang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) revealed an in-situ dynamic carbonization method to synthesize molybdenum carbide in reverse water-gas shift (RWGS) reaction. This study was published in Angewandte Chemie International Edition.In-situ carbonization process of the Mo-based catalyst during RWGS reaction for unprecedented high CO formation (Image by DU xiangze)The researchers discovered that introducing intercalated hydrogen into MoO3 to form HxMoOy promoted its reduction, enabling in-situ carburization at 500 ℃ during the RWGS reaction. This carbonization process produced highly active molybdenum carbide, which exhibited enhanced activity in the RWGS reaction.The researchers indicated that both the surface properties of the catalysts and the reaction microenvironment affected the carbonization process. Specifically, a low O/Mo ratio of the catalyst was more favorable to carbonization, while a high CO2 conversion rate, or a high CO partial pressure, further enhanced the carbonization process.Moreover, the researchers demonstrated that carbonization significantly improved CO2 adsorption and activation, thereby enhancing the activity of the RWGS reaction. This in-situ carburization strategy provided insights into the synthesis of metal carbides in a carbon-containing reaction atmosphere."The structural evolution of the catalyst plays an important role during the reaction, which can be used to enhance the catalytic performance by the rational control strategy," said Prof. FU.This work was supported by the National Key R&D Program of China, the National Natural Science Foundation of China, and the Photon Science Center for Carbon Neutrality.