Photocatalytic reactions that produce solar fuels through water splitting and carbon dioxide reduction offer a promising pathway for solar fuel production. A typical photocatalytic reaction consists of a complex sequence, among which the separation of photogenerated charges is a critical and long-standing challenge. This challenge limits the catalytic activity of photocatalysts and the efficiency of solar-to-chemical energy conversion, as it involves the movement of photogenerated charges across various temporal and spatial scales.Recently, a joint research team led by Prof. JIN Shengye, Prof. TIAN Wenming, Prof. LI Rengui, and Prof. LI Can from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has visualized the ultrafast charge separation process in facet-engineered photocatalyst crystals by using a home-built pump-probe transient reflection microscope (TRM). The study was published in the Journal of the American Chemical Society.Schematic illustration of spatiotemporal mapping measurements as well as the electron and hole density distribution (Image by TIAN Wenming)The researchers employed TRM to directly observe the temporal and spatial evolution of photogenerated electrons and holes on the surface of a typical photocatalyst: facet-engineered bismuth vanadate (BiVO4).The researchers demonstrated that the anisotropic built-in field within BiVO4 crystals facilitated the separation of photogenerated electrons and holes toward different facets through a two-step process spanning various timescales. Initially, the electrons and holes underwent ultrafast separation within around 6 picoseconds, with the electrons converting into localized small polarons after migrating toward the {010} facets of the truncated BiVO4 octahedral crystals. In contrast, the photogenerated holes prolong their separation, moving in a drift-diffusion manner over approximately 2,000 picoseconds before eventually accumulating on the {120} facets.Furthermore, the researchers analyzed the charge separation dynamics and demonstrated that such ultrafast separation could offer an unexpected route to enhance charge separation efficiency in BiVO4 crystals, supporting good photocatalytic performance.This work was supported by the National Natural Science Foundation of China, the CAS Projects for Young Scientists in Basic Research, the Liaoning Revitalization Talents Program, and the Fundamental Research Funds for the Central Universities.

A research group led by Prof. ZHANG Tao, Prof. ZHENG Mingyuan, and Prof. WANG Aiqin from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with SinoSci Bio-EG (Zhengzhou) New Energy Technology Co., Ltd., has launched a trial for the industrial production of ethylene glycol (EG) from biomass with a production capacity of 1,000 metric tons per year.Their technique, known as DLEG technology, used catalytic conversion of biomass to bio-EG. The developed pilot plant passed evaluation by the China Petroleum and Chemical Industry Federation on Oct. 17th.EG is a major bulk chemical with a global consumption of over 30 million tons annually. It is widely used in the synthesis of polyester fibers, bottle chips, antifreeze, paints, and pharmaceuticals. China is the world’s largest producer and consumer, with annual usage exceeding 20 million tons.Traditionally, EG is produced from petroleum or coal, which has several drawbacks, including the use of non-renewable feedstocks, high CO₂ emissions, and significant energy consumption.In 2008, prof. ZHANG’s team introduced a method for the direct catalytic conversion of cellulose into EG, offering a new pathway for bio-EG production. Over the years, the team has carried out systematic research on the DLEG process, focusing on both fundamental understanding and industrial applications.A bio-EG pilot plant at a scale of 1000-ton/a (Image by DICP)In 2019, Prof. ZHANG' team and collaborators began constructing a 1000-ton pilot plant for the DLEG process. By early 2022, they established the world’s first 1,000-ton bio-EG pilot plant in Puyang, Henan. They finished the 72-hour on-site trial of the DLEG pilot plant in Oct., 2023.The results indicated that the reaction selectivity for EG was nearly 80%, with the bio-EG product reaching 99.9% purity. The ultraviolet transmittance value of bio-EG also met national standards for PET polyester synthesis. The DLEG technology demonstrated better economic viability than existing bio-EG methods that use the bio-ethanol-ethylene route. Furthermore, the DLEG process is comparable to petroleum-based EG and superior to coal-based EG commonly used in China.The pilot plant used sugars derived from starch and corn stalks as biomass feedstock for bio-EG production, employing a highly selective catalytic reaction system and an efficient product separation process. It demonstrated the advantages of a short process, mild reaction conditions, and high atom economy, contributing to a green, low-carbon circular economy route for EG production.“The DLEG technology will support China's sustainable economic development and the realization of the nation's ‘dual carbon’ goal, which refers to peaking its carbon dioxide emissions by 2030 and achieving carbon neutrality by 2060”, said Prof. ZHENG Mingyuan.

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.