This work explored the role of defective sites on the hydroformylation of n-butene through ligand regulation. The investigation examined the effect of modulator properties on defect sites and rhodium loading, and optimized the H2BDC/modulator ratio to improve catalyst activity. Atomically dispersed Rh is anchored to these highly dispersed defect sites, effectively preventing aggregation and thereby enhancing hydrogenation ability. Under optimal conditions, the catalyst achieved a conversion of 96.9 %, with an overall aldehyde selectivity of 90 %. DRIFTS analysis provided compelling evidence that Rh(CO)2 and HRhCO species were formed on 1Rh/MOF-5-HBC, improving CO insertion capability. This study highlights the significance of MOFs as catalyst supports in enhancing performance through defect engineering. The ability of the modulator to induce defect formation was measured by pKa. Meanwhile, it has been discovered that the length differences between the modulator and the MOF organic ligand can have a significant impact on the stability of defective MOFs.

Colorimetric sensor arrays (CSAs) can detect the volatile organic compounds (VOCs) produced during food storage, enabling odor visualization for freshness monitoring. Herein, sixteen chemo-responsive dyes that undergo observable color changes to VOCs are absorbed on ammonium quaternized cellulose nanofibres (C-CNFs) to design a paper -based CSA. The strong ionic interactions between the dyes and C-CNFs immobilize the dyes onto the sensor without leakage and provide stable and consistent colorimetric change even at a high relative humidity (RH = 60 %). Owing to the three-dimensional porous structure of C-CNFs, the CSA demonstrates high sensitivity for detecting VOCs produced during shrimp and fish spoilage. The limits of detection for ammonia, dimethylamine, trimethylamine, cadaverine, and putrescine are 2, 21, 3, 1, and 1 ppm, respectively. By selecting dyes covering a wide range of VOCs, the color changes in the CSA can accurately differentiate fresh, less fresh, slightly spoilt, and spoilt shrimp and fish. These color changes are further digitized and used to train a convolutional neural network (CNN). The CNN method has high accuracy (99 %) for determining abovementioned freshness levels. The combination of CSA and CNN is a promising approach for fabricating a portable sensing platform for the advanced non-destructive determination of food freshness levels.

Exploring efficient and low-cost oxygen evolution reaction (OER) electrocatalysts is of crucial importance. Here, we report a surface plasmon resonance (SPR) engineering strategy to regulate surface reconstruction of CoFeB nanosheets by decorating plasmonic MoO2 nanospheres (MoO2/CoFeB), in which the SPR effect of MoO2 offers an additional acceleration for the conversion of inactive Co species to active cobalt oxyhydroxide on the CoFeB surface under visible light. Our results also indicate the real reactive surface for CoFeB is in the form of CoFeOOH with adsorbed BO2- that has positive effect. The MoO2/CoFeB shows superior OER performance with a low overpotential (209 mV at J=10 mA cm(-2)). However, such an accelerated reconstruction behavior would be self-terminated once the anodic voltage increases to thoroughly oxidize the MoO2 to high valence state (+6). This work inspires us to develop a rational strategy to improve the catalytic performance by properly regulating the surface reconstruction.

Immobilization of the Rh active sites in novel porous materials has attracted attentions for solving the problems of separation and recycling of homogeneous catalysts. In this work, a comparative study of phosphine modified 1Rh/MOF-5 using three different methods was reported, namely 1Rh-P/MOF-5, 1Rh/MOF-5-P and 1Rh/MOF-5-PPh3. Similar with the traditional methods, PPh3 was etched on Rh particles by impregnation in 1Rh-P/MOF-5 and encapsulated in the pores by solvothermal method in 1Rh/MOF-5-P. Moreover, we proposed a novel post-synthesis strategy for grafting phenyl phosphine on the organic linkers in 1Rh/MOF-5-PPh3. The position of phenyl phosphine in MOFs and the effect of phosphine on the Rh active sites in hydroformylation were investigated by XRD, IR, XPS, TGA and DRIFTS. 1Rh/MOF-5-PPh3 exhibited the best catalytic activity and stability than 1Rh-P/MOF-5 and 1Rh/MOF-5-P in the hydroformylation of 1-butene. Different P/Rh ratio in P-modified 1Rh/MOF-5 led to the spatial environment change around the Rh active sites. This study showed details in the role of phosphine ligands played in hydroformylation reactions and provided some guidance for MOFs materials in the immobilization of homogeneous catalysts.

Electrochemical reduction of CO2 (CO2 RR) into value-added products is a promising strategy to reduce energy consumption and solve environmental issues. Formic acid/formate is one of the high-value, easy-to-collect, and economically viable products. Herein, the reconstructed Bi2 O2 CO3 nanosheets (BOCR NSs) are synthesized by an in situ electrochemical anion exchange strategy from Bi2 O2 SO4 as a pre-catalyst. The BOCR NSs achieve a high formate Faradaic efficiency (FEformate ) of 95.7% at -1.1 V versus reversible hydrogen electrode (vs. RHE), and maintain FEformate above 90% in a wide potential range from -0.8 to -1.5 V in H-cell. The in situ spectroscopic studies reveal that the obtained BOCR NSs undergo the anion exchange from Bi2 O2 SO4 to Bi2 O2 CO3 and further promote the self-reduction to metallic Bi to construct Bi/BiO active site to facilitate the formation of OCHO* intermediate. This result demonstrates anion exchange strategy can be used to rational design high performance of the catalysts toward CO2 RR.

In this work, three MOF-based materials with highly dispersed Rh(I) were synthesized for hydroformylation of n-butene, namely Rh(I)/UiO-66, Rh(I)/MOF-5 and Rh(I)/MIL-101. The defect sites on the metal nodes of MOFs promoted the anchoring of Rh as a single active site. A high-performance Rh(I)/MOF-5 catalyst was obtained with the n-butene conversion and pentanal selectivity of 96.4% and 85.8%, respectively. In addition, it showed a good stability in the recycling tests after five runs. XRD, TEM, XPS, in situ DRIRTS confirmed that the metal nodes in MOFs modified the activity of the coordinated Rh catalyst by influencing the adsorption strength of CO. Combing the DFT results, we predicted that Rh(I)/MOF-5 catalyst with suitable CO adsorption energy could reduce the reaction energy barrier in CO insertion process, which was the rate-determining step of overall reaction, thus improving the selectivity of total aldehydes. This work broadened the application of MOFs as catalyst supports and provided assistance for the development of heterogeneous catalysts in hydroformylation of olefins.

Immobilization of the Rh active sites in novel porous materials has attracted attentions for solving the problems of separation and recycling of homogeneous catalysts. In this work, a comparative study of on phosphine modified Rh/MOF-5 using three different methods was reported, namely Rh-P/MOF-5, Rh/MOF-5-P and Rh/MOF-5-PPh3. Similar with traditional methods, PPh3 was etched on Rh particles by impregnation in Rh-P/MOF-5 and encapsulated in the pores by solvothermal method in Rh/MOF-5-PPh3. Moreover, we proposed a novel post-synthesis strategy for grafting phenyl phosphine on the organic linkers in Rh/MOF-5-PPh3. The position of phenyl phosphine in MOFs and the effect of phosphine on the Rh active sites in hydroformylation were investigated by XRD, IR, XPS, TGA and DRIFTS. Rh/MOF-5-PPh3 exhibited the best catalytic activity and stability than Rh-P/MOF-5 and Rh/MOF-5-P in the hydroformylation of n-butene. Different P/Rh ratio in P-modified Rh/MOF-5 led to the spatial environment change around the Rh active sites with the help of the fixed structure of MOFs. This study showed details in the role of phosphine ligands played in hydroformylation reactions and provided some guidance for MOFs materials in the immobilization of homogeneous catalysts.

Alkali metals have been widely studied to improve the efficiency of CO2 hydrogenation to light olefins on iron-based catalysts. Herein, a series of Rb-promoted Fe3O4 microsphere catalysts were developed to understand the effects of Rb promoter on the catalytic performance. The 3wt%Rb/Fe3O4 catalyst showed high selectivity of light olefins (C2–C4, 47.4%) with a high olefin/paraffin ratio (10.7). XRD, H2-TPR, CO2-TPD, XPS analyses show that the proper Rb loading rate may adjust carbonaceous species content and ferric oxide content on the surface of the catalyst which is help for the synergistic effect to produce light olefins.

The two-dimensional black phosphorus can interact with metal compounds to form BP–M composites, showing tailored properties. This review summarizes BP–Ms in different applications, revealing the challenges and prospects of this composite material.

The synergic effects of iron carbides and iron oxides were used to adjust the reaction pathway to form alkenes or ethanol.

The oxygen evolution reaction (OER) plays a paramount role in a variety of electrochemical energy conversion devices, and the exploration of highly active, stable, and low-cost electrocatalysts is one of the most important topics in this field. The exfoliated black phosphorus (EBP) nanosheet with a two-dimensional (2D) layered structure has high carrier mobility but is limited by excessive oxygen-containing intermediate absorption and fast deterioration in air. We here report the fabrication of nanohybrids of amorphous CoFeB nanosheets on EBP nanosheets (EBP/CoFeB). The 2D/2D heterostructure, thanks to the electronic interactions and oxygen affinity difference between EBP and CoFeB nanosheets, is capable of balancing the oxygen-containing intermediate absorption to an optimal status for facilitating the OER process. While the crystalline EBP contributes to the improved conductivity, the amorphous coating protects EBP and thus ensures the catalytic stability. The EBP/CoFeB electrocatalyst shows excellent OER performance with an ultralow overpotential of 227 mV at 10 mA cm(-2) with an ultrasmall Tafel slope of 36.7 mV dec(-1) with excellent stability. This study may inspire more researches to develop heterostructured nanohybrid electrocatalysts for a diversity of electrochemical reactions.

Exploring the structure of iron-based catalysts on the catalytic performance of Fischer-Tropsch synthesis (FTS) reaction has attracted much attention. With this in mind, the mixture of SiO2 or Al2O3 powder and non-porous iron oxide powder (alpha-Fe2O3) have been investigated for understanding the nature role of different iron carbides in the FTS reaction by adjusting the formation of iron carbides. Under the typical FTS reaction conditions, the CO conversion of Al2O3/alpha-Fe2O3 = 1 catalyst could reach up to 61.6 %, which is about 3.3 times that of the pure alpha-Fe2O3 catalyst. Based on the characterization results, including in situ XPS and CO-DRIFTS as well as Mossbauer spectra, it is found that the electronic state of iron atoms is affected by the existence of SiO2 or Al2O3, and the interactions of Fe-Si or Fe-Al are formed on the surface of iron powder, which plays an important role in formation of C-rich iron carbide active phase (epsilon-Fe2C). Although chi-Fe5C2 is usually as the active phase in the FTS reaction, we have found that the content of epsilon-Fe2C is more positive to activity.

The present work reports a general approach to improve the electrocatalytic property of noble metal through regulating its electron status by introducing the electronic metalsupport interaction (EMSI). As a case study, the catalytic activity of metallic Pd toward oxygen evolution reaction (OER) in alkaline solution has been significantly promoted by stabilizing Pd delta+ oxidic species at the interface of the Pd-metal oxide support with the help of EMSI effect, suggesting an intrinsic advantage of Pd delta+ in driving OER. We further demonstrate that the chemical state of Pd delta+ can be easily modulated in the range of 2+ to 3+ by changing the metal oxide support, interestingly, accompanied by a clear dependence of the OER activity on the oxidation state of Pd delta+. The high Pd3+ species-containing Fe2O3/Pd catalyst has fed an impressively enhanced OER property, showing an overpotential of 383 mV at 10 mA cm(2) compared to those of >600 mV on metallic Pd and 540 mV on Fe2O3/glassy carbon. The greatly enhanced OER performance is believed to primarily derive from the distinctive improvement in the adsorption of oxygenated intermediates (e.g., *OH and *OOH) on metal-oxide/Pd catalysts. Moreover, similar EMSI induced improvements in OER activity in alkaline solution are also achieved on both of the Fe2O3/Au and Fe2O3/Pt, which possess the oxidic species of Au3+, and Pt2+ and Pt4+, respectively.

Dynamic rheological measurements indicate that supra-molecules, polymers and carbogenic nanoparticles are generated successively during pyrolysis of citric acid based nanodots.