Benedict N. Leidecker, Dilver Peña Fuentes, Matthias König, Jiali Liu, Wolfgang Baumann, Mathias Sawall, Klaus Neymeyr, Haijun Jiao, Robert Franke, Armin Börner, Christoph Kubis
Structural and dynamic properties of BiPhePhos modified rhodium complexes under hydroformylation conditions have been investigated in detail by using high-pressure (HP) in situ transmission IR- and NMR-spectroscopy. An experiment design approach which combines component/reagent perturbations, in situ-FTIR measurements and chemometric peak group analysis (PGA) led to the identification of most relevant components. The ligand coordination in the structures of the hydrido and acyl 18-VE resting state complexes has been elucidated. The hydrido complex of the type e,e-[HRh(CO)2(P∩P)] represents the dominant resting state after catalyst preformation and during the n-regioselective hydroformylation. Dimer formation only takes place to a minor extent under severe reaction conditions under hydrogen depletion. Mono- and dinuclear hydrido monocarbonyl complexes are formed at higher ligand-to-metal ratios and low partial pressures of carbon monoxide. Both stereoisomeric forms of the bisphosphite modified acyl complexes e,a-[RC(O)Rh(CO)2(P∩P)] and e,e-[RC(O)Rh(CO)2(P∩P)] are generated as an equilibrium mixture.
{"title":"In situ spectroscopic investigations on BiPhePhos modified rhodium complexes in alkene hydroformylation","authors":"Benedict N. Leidecker, Dilver Peña Fuentes, Matthias König, Jiali Liu, Wolfgang Baumann, Mathias Sawall, Klaus Neymeyr, Haijun Jiao, Robert Franke, Armin Börner, Christoph Kubis","doi":"10.1039/d4cy00481g","DOIUrl":"https://doi.org/10.1039/d4cy00481g","url":null,"abstract":"Structural and dynamic properties of BiPhePhos modified rhodium complexes under hydroformylation conditions have been investigated in detail by using high-pressure (HP) <em>in situ</em> transmission IR- and NMR-spectroscopy. An experiment design approach which combines component/reagent perturbations, <em>in situ</em>-FTIR measurements and chemometric peak group analysis (PGA) led to the identification of most relevant components. The ligand coordination in the structures of the hydrido and acyl 18-VE resting state complexes has been elucidated. The hydrido complex of the type <em>e</em>,<em>e</em>-[HRh(CO)<small><sub>2</sub></small>(P∩P)] represents the dominant resting state after catalyst preformation and during the <em>n</em>-regioselective hydroformylation. Dimer formation only takes place to a minor extent under severe reaction conditions under hydrogen depletion. Mono- and dinuclear hydrido monocarbonyl complexes are formed at higher ligand-to-metal ratios and low partial pressures of carbon monoxide. Both stereoisomeric forms of the bisphosphite modified acyl complexes <em>e</em>,<em>a</em>-[RC(O)Rh(CO)<small><sub>2</sub></small>(P∩P)] and <em>e</em>,<em>e</em>-[RC(O)Rh(CO)<small><sub>2</sub></small>(P∩P)] are generated as an equilibrium mixture.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anchoring of NiCox alloy nanoparticles (NPs) onto nitrogen vacancy-rich carbon nitride nanotubes (NiCox/VN-CNNTs) with porous structure was well designed toward promoting efficiently photocatalytic conversion of CO2 into solar fuels in the presence of water vapor. NiCox/VN-CNNTs exhibit not only highly efficient generation of CO, but also a significant amount of CH4, compared to only CO and a trace amount of CH4 on pristine VN-CNNTs and single metal-loading VN-CNNTs. The photoexcited dynamics show that the synergy modulation of the NiCox alloy site and vacancy leverage of CNNT is beneficial for efficient separation of photoinduced electron–hole pairs, in favor of the multiple electron-involving reduction pathways for CH4 formation. Density functional theory simulations validate that the loaded NiCox alloy NPs also provide the driving force for accelerating the absorption of CO2, reducing the free energy of CO2-to-CH4 photoreduction, and decreasing desorption energy of the forming CH4. This work presents a viewpoint to engineer the composition of nanoalloy-based photocatalysts for improved CO2-to-CH4 photoreduction.
将 NiCox 合金纳米颗粒（NPs）锚定到具有多孔结构的富氮空位氮化碳纳米管（NiCox/VN-CNNTs）上的设计很好，可以促进在有水蒸气存在的情况下将二氧化碳高效光催化转化为太阳能燃料。与原始 VN-CNT 和单一金属负载 VN-CNT 只生成 CO 和微量 CH4 相比，NiCox/VN-CNNT 不仅能高效生成 CO，还能生成大量 CH4。光激发动力学表明，NiCox 合金位点和 CNNT 空位杠杆的协同调制有利于光诱导电子-空穴对的有效分离，有利于多种电子参与的还原途径形成 CH4。密度泛函理论模拟验证了负载的镍氧化物合金 NPs 还能提供加速吸收 CO2 的驱动力，降低 CO2 转化为 CH4 光还原的自由能，并降低形成 CH4 的解吸能。这项研究提出了一种观点，即通过设计纳米合金光催化剂的组成来改善 CO2 到 CH4 的光还原。
{"title":"Anchoring of NiCox alloy nanoparticles on nitrogen vacancy-rich carbon nitride nanotubes toward promoting efficiently photocatalytic CO2 conversion into solar fuel","authors":"Qingqing Zhang, Bo Tao, Chen Zhao, Zongyan Zhao, Hui Wu, Xiaohui Zhong, Zhigang Zou, Yong Zhou","doi":"10.1039/d4cy00626g","DOIUrl":"https://doi.org/10.1039/d4cy00626g","url":null,"abstract":"Anchoring of NiCo<small><sub><em>x</em></sub></small> alloy nanoparticles (NPs) onto nitrogen vacancy-rich carbon nitride nanotubes (NiCo<small><sub><em>x</em></sub></small>/V<small><sub>N</sub></small>-CNNTs) with porous structure was well designed toward promoting efficiently photocatalytic conversion of CO<small><sub>2</sub></small> into solar fuels in the presence of water vapor. NiCo<small><sub><em>x</em></sub></small>/V<small><sub>N</sub></small>-CNNTs exhibit not only highly efficient generation of CO, but also a significant amount of CH<small><sub>4</sub></small>, compared to only CO and a trace amount of CH<small><sub>4</sub></small> on pristine V<small><sub>N</sub></small>-CNNTs and single metal-loading V<small><sub>N</sub></small>-CNNTs. The photoexcited dynamics show that the synergy modulation of the NiCo<small><sub><em>x</em></sub></small> alloy site and vacancy leverage of CNNT is beneficial for efficient separation of photoinduced electron–hole pairs, in favor of the multiple electron-involving reduction pathways for CH<small><sub>4</sub></small> formation. Density functional theory simulations validate that the loaded NiCo<small><sub><em>x</em></sub></small> alloy NPs also provide the driving force for accelerating the absorption of CO<small><sub>2</sub></small>, reducing the free energy of CO<small><sub>2</sub></small>-to-CH<small><sub>4</sub></small> photoreduction, and decreasing desorption energy of the forming CH<small><sub>4</sub></small>. This work presents a viewpoint to engineer the composition of nanoalloy-based photocatalysts for improved CO<small><sub>2</sub></small>-to-CH<small><sub>4</sub></small> photoreduction.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aiming to achieve a better understanding of the interactions between photonic crystals (PCs) built of semiconductor TiO2 and metallic nanostructures (MNSs), we studied the effect of combining the slow photon effects (SFE) occurring in the PC structure and electron trapping taking place in MNSs on the photocatalytic decomposition of a model pollutant – rhodamine B (RhB). PCs of small (203 nm), medium (316 nm) and large (493 nm) pore size were prepared with the use of the sol–gel method supported by the self-assembly of polystyrene (PS) microspheres that served as a template. Silver, platinum, and bimetallic silver–platinum nanostructures (AgNSs, PtNSs and AgPtNSs) were generated on the surface of TiO2 PCs by photoreduction of appropriate ions under UV illumination. It was found that an increase of the pore size of PCs only changes slightly the position of the semiconductor band gap (BG), while it particularly affects the photonic band gap (PBG), shifting it towards longer wavelengths. The modification of PCs with metallic nanostructures increases the intensity of the PBG. Moreover, the phenomenon of overlapping of the PBG edge with the semiconductor BG and the applied illumination range (known as the slow photon effect (SPE) combined with the electron trapping that is the result of modification of PCs with mono- and bi-metallic nanostructures) leads to an increase in the photocatalytic activity of PCs.
为了更好地理解由半导体二氧化钛（TiO2）和金属纳米结构（MNS）构成的光子晶体（PC）之间的相互作用，我们研究了 PC 结构中发生的慢光子效应（SFE）和 MNS 中发生的电子捕获相结合对模型污染物罗丹明 B（RhB）光催化分解的影响。利用溶胶-凝胶法，在作为模板的聚苯乙烯（PS）微球自组装的支持下，制备了小孔（203 nm）、中孔（316 nm）和大孔（493 nm）的 PC。在紫外光照射下，通过适当离子的光还原作用，在 TiO2 PC 表面生成了银、铂和银铂双金属纳米结构（AgNSs、PtNSs 和 AgPtNSs）。研究发现，增大 PC 的孔径只会轻微改变半导体带隙（BG）的位置，但会特别影响光子带隙（PBG），使其向长波长方向移动。用金属纳米结构修饰 PC 会增加 PBG 的强度。此外，PBG 边缘与半导体 BG 和应用光照范围重叠的现象（称为慢光子效应 (SPE)）与单金属和双金属纳米结构修饰 PC 所产生的电子捕获相结合，也会导致 PC 的光催化活性提高。
{"title":"Preparation and photocatalytic activity of TiO2 photonic crystals modified by bimetallic Ag–Pt nanostructures","authors":"Joanna Stępnik, Aneta Kisielewska, Ireneusz Piwoński","doi":"10.1039/d4cy00307a","DOIUrl":"https://doi.org/10.1039/d4cy00307a","url":null,"abstract":"Aiming to achieve a better understanding of the interactions between photonic crystals (PCs) built of semiconductor TiO<small><sub>2</sub></small> and metallic nanostructures (MNSs), we studied the effect of combining the slow photon effects (SFE) occurring in the PC structure and electron trapping taking place in MNSs on the photocatalytic decomposition of a model pollutant – rhodamine B (RhB). PCs of small (203 nm), medium (316 nm) and large (493 nm) pore size were prepared with the use of the sol–gel method supported by the self-assembly of polystyrene (PS) microspheres that served as a template. Silver, platinum, and bimetallic silver–platinum nanostructures (AgNSs, PtNSs and AgPtNSs) were generated on the surface of TiO<small><sub>2</sub></small> PCs by photoreduction of appropriate ions under UV illumination. It was found that an increase of the pore size of PCs only changes slightly the position of the semiconductor band gap (BG), while it particularly affects the photonic band gap (PBG), shifting it towards longer wavelengths. The modification of PCs with metallic nanostructures increases the intensity of the PBG. Moreover, the phenomenon of overlapping of the PBG edge with the semiconductor BG and the applied illumination range (known as the slow photon effect (SPE) combined with the electron trapping that is the result of modification of PCs with mono- and bi-metallic nanostructures) leads to an increase in the photocatalytic activity of PCs.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Environmental concerns have emphasized the necessity of pursuing renewable energy in order to reduce reliance on fossil fuel-derived sources. Biodiesel, a promising renewable fuel, still faces challenges in its production associated with the feedstock and the dependence on homogeneous catalysts. Herein, for the first time, sodium citrate, a bio-based and environmentally friendly compound, is calcined at mild temperatures to create a novel basic heterogeneous catalyst for the transesterification of refined canola and waste cooking oils. The catalyst demonstrated excellent performance with a 99% conversion of canola oil. Moreover, a conversion of 98% was obtained under optimized conditions (1 : 36 oil to methanol molar ratio, 10 wt% catalyst loading, 3 h, and 90 °C) when waste cooking oil was used as the feedstock. The catalyst further exhibited remarkable tolerance up to 10 wt% free fatty acids. Kinetics studies indicated that the reaction is governed by a pseudo-first-order kinetic model. Notably, the catalyst exhibits high turnover frequencies of 6.22 h−1 and 1.86 h−1 for the transesterification of canola and waste cooking oils, respectively, proving its efficiency. Finally, a possible mechanism for the reaction using calcined sodium citrate as a basic heterogeneous catalyst was proposed.
{"title":"Exploiting the potential of calcined sodium citrate as a novel and efficient heterogeneous catalyst for biodiesel synthesis","authors":"Michelle Pains Duarte, Rafik Naccache","doi":"10.1039/d4cy00195h","DOIUrl":"https://doi.org/10.1039/d4cy00195h","url":null,"abstract":"Environmental concerns have emphasized the necessity of pursuing renewable energy in order to reduce reliance on fossil fuel-derived sources. Biodiesel, a promising renewable fuel, still faces challenges in its production associated with the feedstock and the dependence on homogeneous catalysts. Herein, for the first time, sodium citrate, a bio-based and environmentally friendly compound, is calcined at mild temperatures to create a novel basic heterogeneous catalyst for the transesterification of refined canola and waste cooking oils. The catalyst demonstrated excellent performance with a 99% conversion of canola oil. Moreover, a conversion of 98% was obtained under optimized conditions (1 : 36 oil to methanol molar ratio, 10 wt% catalyst loading, 3 h, and 90 °C) when waste cooking oil was used as the feedstock. The catalyst further exhibited remarkable tolerance up to 10 wt% free fatty acids. Kinetics studies indicated that the reaction is governed by a pseudo-first-order kinetic model. Notably, the catalyst exhibits high turnover frequencies of 6.22 h<small><sup>−1</sup></small> and 1.86 h<small><sup>−1</sup></small> for the transesterification of canola and waste cooking oils, respectively, proving its efficiency. Finally, a possible mechanism for the reaction using calcined sodium citrate as a basic heterogeneous catalyst was proposed.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding reaction mechanisms of metal-catalyzed processes is of paramount importance for the design of superior catalysts that circumvent unproductive pathways, while accelerating catalyst discovery. In this respect, gaining mechanistic understanding for reactions carried out at high pressures of gas reagents remains a major limitation because special setups are typically required, which is the case for metal-catalyzed direct reductive aminations (DRA) under high H2 pressure. To overcome this issue, extensive computational calculations have been herein conducted for the iridium-catalyzed DRA between aliphatic ketones and aliphatic secondary amines. This highly atom-economic reaction delivers only water as side-product and it is relevant for the identification of active pharmaceutical ingredients. In this contribution, we highlight that the excellent reactivity encountered with very different P,P-chelating ligands results from the fact that two different mechanistic pathways operate for each system. In addition, we found that the key hydride transfer step is more accessible with a penta-coordinated iridium complex rather than with the expected hexa-coordinated iridium species using a Josiphos-type ligand when compared to the large bite-angle Xantphos. For comparison purposes, we also evaluated a related Josiphos-type ligand and a small bite-angle diphosphane.
{"title":"Penta- versus hexa-coordinated iridium catalysts control the reactivity of the direct reductive amination between aliphatic amines and aliphatic ketones: a DFT-guided mechanism","authors":"Hao Lin, Longfei Li, Lanbo Liu, Zhihui Li, Thi-Mo Nguyen, Matthieu Jouffroy, Rafael Gramage-Doria","doi":"10.1039/d4cy00516c","DOIUrl":"https://doi.org/10.1039/d4cy00516c","url":null,"abstract":"Understanding reaction mechanisms of metal-catalyzed processes is of paramount importance for the design of superior catalysts that circumvent unproductive pathways, while accelerating catalyst discovery. In this respect, gaining mechanistic understanding for reactions carried out at high pressures of gas reagents remains a major limitation because special setups are typically required, which is the case for metal-catalyzed direct reductive aminations (DRA) under high H<small><sub>2</sub></small> pressure. To overcome this issue, extensive computational calculations have been herein conducted for the iridium-catalyzed DRA between aliphatic ketones and aliphatic secondary amines. This highly atom-economic reaction delivers only water as side-product and it is relevant for the identification of active pharmaceutical ingredients. In this contribution, we highlight that the excellent reactivity encountered with very different P,P-chelating ligands results from the fact that two different mechanistic pathways operate for each system. In addition, we found that the key hydride transfer step is more accessible with a penta-coordinated iridium complex rather than with the expected hexa-coordinated iridium species using a Josiphos-type ligand when compared to the large bite-angle Xantphos. For comparison purposes, we also evaluated a related Josiphos-type ligand and a small bite-angle diphosphane.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The oxidation of styrenes to acetophenones is an industrially relevant transformation that has been traditionally conducted with the Wacker-type reaction using pure oxygen at high temperature and pressure using Pd–Cu catalysts. Herein, we report a Co(II) complex of a salen appended L-diaminoribose-derived ligand that is catalytically active for the room temperature, selective aerial oxidation of styrenes to acetophenones. Further, the in situ generated Co(II) complex (from a mixture of the salen appended L-diaminoribose-derived ligand and a Co(II) salt) is also found to enable the catalysis. The oxidation is efficiently conducted in the presence of Et3SiH as a hydrogen atom transfer (HAT) agent and provides very high isolated yields (71–95%) of the acetophenones. Further, the HAT mediated transformation with NaBH4 also enables the non-aqueous, Markovnikov hydration of styrenes, providing the corresponding benzylic alcohols, exclusively as a single product in over 72–97% isolated yields via an oxidation–reduction mechanism. The methodologies provided very high exclusive yields of the products and were compatible with various substitutions on the aryl ring of the styrene. Detailed experimental and computational studies revealed a structural feature of the ligand that enabled the facile formation and stabilization of a pseudo-octahedral Co(III) intermediate that facilitated the oxidation reaction.
{"title":"A sugar-derived ligand for room temperature aerial oxidation or non-aqueous Markovnikov hydration of styrenes using a preformed or in situ generated Co complex","authors":"Sachchida Nand Pandey, Arunava Sengupta, Rajib Bera, Sohel Ali, Somnath Yadav","doi":"10.1039/d4cy00522h","DOIUrl":"https://doi.org/10.1039/d4cy00522h","url":null,"abstract":"The oxidation of styrenes to acetophenones is an industrially relevant transformation that has been traditionally conducted with the Wacker-type reaction using pure oxygen at high temperature and pressure using Pd–Cu catalysts. Herein, we report a Co(<small>II</small>) complex of a salen appended <small>L</small>-diaminoribose-derived ligand that is catalytically active for the room temperature, selective aerial oxidation of styrenes to acetophenones. Further, the <em>in situ</em> generated Co(<small>II</small>) complex (from a mixture of the salen appended <small>L</small>-diaminoribose-derived ligand and a Co(<small>II</small>) salt) is also found to enable the catalysis. The oxidation is efficiently conducted in the presence of Et<small><sub>3</sub></small>SiH as a hydrogen atom transfer (HAT) agent and provides very high isolated yields (71–95%) of the acetophenones. Further, the HAT mediated transformation with NaBH<small><sub>4</sub></small> also enables the non-aqueous, Markovnikov hydration of styrenes, providing the corresponding benzylic alcohols, exclusively as a single product in over 72–97% isolated yields <em>via</em> an oxidation–reduction mechanism. The methodologies provided very high exclusive yields of the products and were compatible with various substitutions on the aryl ring of the styrene. Detailed experimental and computational studies revealed a structural feature of the ligand that enabled the facile formation and stabilization of a <em>pseudo</em>-octahedral Co(<small>III</small>) intermediate that facilitated the oxidation reaction.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The insufficient performance of non-noble metal catalysts in alkaline media is a prominent issue that limits the widespread adoption of electrocatalytic water splitting. In this study, we present an efficient Mo doping strategy to boost the electrocatalytic performance of NiFe layered double hydroxide (LDH) through modulating the electronic structure of active Ni sites. The optimized Mo doped NiFe-LDH (denoted as NiFeMo-2) exhibits significantly improved activity, showing a smaller overpotential of 262 mV at 10 mA cm−2 compared to NiFe-LDH (344 mV). X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectra demonstrate that the incorporation of Mo not only increases the electron cloud density of Ni, but also induces more oxygen vacancies. Due to these structural modifications, the oxygen evolution reaction (OER) kinetics is dramatically enhanced, confirmed by in situ electrochemical impedance spectroscopy (EIS). Moreover, in situ Raman spectroscopy shows that the Mo doping can facilitate the formation of active NiOOH species at a lower potential, thus accelerating the OER kinetics. The in situ differential electrochemical mass spectrometry (DEMS) technique with 18O isotope labelling, tetraalkylammonium cation (TMA+) chemical probe, and ethanol oxidation reaction suggest that the NiFeMo-LDH catalyst primarily follows the adsorbate evolution mechanism (AEM) pathway, the promoted dehydrogenation process with the modulation of *OH adsorption. This study reports a high-performance non-noble metal OER electrocatalyst and unveils the origins of metal doping to enhance the OER kinetics.
非贵金属催化剂在碱性介质中的性能不足是限制电催化分水技术广泛应用的一个突出问题。在本研究中，我们提出了一种高效的钼掺杂策略，通过调节活性镍位点的电子结构来提高镍铁层双氢氧化物（LDH）的电催化性能。优化后的掺杂钼的镍铁层双氢氧化物（NiFe-LDH，代号为 NiFeMo-2）的活性得到了显著提高，与镍铁层双氢氧化物（NiFe-LDH，代号为 344 mV）相比，在 10 mA cm-2 的条件下，过电位仅为 262 mV。X 射线光电子能谱（XPS）和电子顺磁共振（EPR）光谱表明，掺入 Mo 不仅增加了镍的电子云密度，还诱导了更多的氧空位。原位电化学阻抗光谱（EIS）证实，由于这些结构改性，氧进化反应（OER）动力学显著增强。此外，原位拉曼光谱显示，钼掺杂能在较低电位下促进活性 NiOOH 物种的形成，从而加速了氧演化反应的动力学过程。利用 18O 同位素标记、四烷基铵阳离子（TMA+）化学探针和乙醇氧化反应进行的原位差分电化学质谱（DEMS）技术表明，NiFeMo-LDH 催化剂主要遵循吸附剂进化机制（AEM）途径，即在*OH 吸附调控下的促进脱氢过程。本研究报告了一种高性能非贵金属 OER 电催化剂，并揭示了金属掺杂增强 OER 动力学的起源。
{"title":"Facilitating active NiOOH formation via Mo doping towards high-efficiency oxygen evolution","authors":"Liuqing Wang, Jinsheng Li, Qinglei Meng, Meiling Xiao, Changpeng Liu, Wei Xing, Jianbing Zhu","doi":"10.1039/d4cy00314d","DOIUrl":"https://doi.org/10.1039/d4cy00314d","url":null,"abstract":"The insufficient performance of non-noble metal catalysts in alkaline media is a prominent issue that limits the widespread adoption of electrocatalytic water splitting. In this study, we present an efficient Mo doping strategy to boost the electrocatalytic performance of NiFe layered double hydroxide (LDH) through modulating the electronic structure of active Ni sites. The optimized Mo doped NiFe-LDH (denoted as NiFeMo-2) exhibits significantly improved activity, showing a smaller overpotential of 262 mV at 10 mA cm<small><sup>−2</sup></small> compared to NiFe-LDH (344 mV). X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectra demonstrate that the incorporation of Mo not only increases the electron cloud density of Ni, but also induces more oxygen vacancies. Due to these structural modifications, the oxygen evolution reaction (OER) kinetics is dramatically enhanced, confirmed by <em>in situ</em> electrochemical impedance spectroscopy (EIS). Moreover, <em>in situ</em> Raman spectroscopy shows that the Mo doping can facilitate the formation of active NiOOH species at a lower potential, thus accelerating the OER kinetics. The <em>in situ</em> differential electrochemical mass spectrometry (DEMS) technique with <small><sup>18</sup></small>O isotope labelling, tetraalkylammonium cation (TMA<small><sup>+</sup></small>) chemical probe, and ethanol oxidation reaction suggest that the NiFeMo-LDH catalyst primarily follows the adsorbate evolution mechanism (AEM) pathway, the promoted dehydrogenation process with the modulation of *OH adsorption. This study reports a high-performance non-noble metal OER electrocatalyst and unveils the origins of metal doping to enhance the OER kinetics.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141528922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The synthesis of high activity atomically precise nanoclusters is crucial to understand structure–property relationships in environmentally friendly reactions. However, Pd nanoclusters have been rarely reported due to their susceptibility to oxidization. In this work, Pdn nanoclusters protected by bis[2-(diphenylphosphino)phenyl] ether (DPEphos) have been synthesized and fully characterized by electrospray ionization mass spectrometry (ESI-MS) and HAADF-STEM. In the hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF), which is an important candidate for liquid fuels, the supported Pdn nanoclusters show great catalytic performance with a yield of 94.1% under mild conditions. The theoretical investigations reveal that, in the phosphate protected Pdn system, the desorption of DMF is the rate-determining step. And compared with the Pd catalyst coordinated with PPh3, the Pdn catalyst protected by DPEphos has a modest desorption ability of DMF, leading to the high yield of DMF. This work presents the synthesis and application of a Pdn catalyst with bidentate phosphine ligands, which could contribute to the development of rational design of effective catalysts in biomass and energy conversion.
{"title":"Selective hydrogenation of 5-hydroxymethylfurfural over bidentate phosphine protected Pdn nanoclusters","authors":"Jie Tang, Chao Liu, Xiaorui Liu, Yaning Han, Tingting Ge, Cuiping Yu, Daxin Liang, Jing Xu, Jiahui Huang","doi":"10.1039/d4cy00303a","DOIUrl":"https://doi.org/10.1039/d4cy00303a","url":null,"abstract":"The synthesis of high activity atomically precise nanoclusters is crucial to understand structure–property relationships in environmentally friendly reactions. However, Pd nanoclusters have been rarely reported due to their susceptibility to oxidization. In this work, Pd<small><sub><em>n</em></sub></small> nanoclusters protected by bis[2-(diphenylphosphino)phenyl] ether (DPEphos) have been synthesized and fully characterized by electrospray ionization mass spectrometry (ESI-MS) and HAADF-STEM. In the hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF), which is an important candidate for liquid fuels, the supported Pd<small><sub><em>n</em></sub></small> nanoclusters show great catalytic performance with a yield of 94.1% under mild conditions. The theoretical investigations reveal that, in the phosphate protected Pd<small><sub><em>n</em></sub></small> system, the desorption of DMF is the rate-determining step. And compared with the Pd catalyst coordinated with PPh<small><sub>3</sub></small>, the Pd<small><sub><em>n</em></sub></small> catalyst protected by DPEphos has a modest desorption ability of DMF, leading to the high yield of DMF. This work presents the synthesis and application of a Pd<small><sub><em>n</em></sub></small> catalyst with bidentate phosphine ligands, which could contribute to the development of rational design of effective catalysts in biomass and energy conversion.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zekai Zhang, Wei Yan, Ying Wang, Guokai Cui, Hanfeng Lu
Photocatalytic reduction of CO2 with solar energy can realize a carbon cycle and ultimately this could solve the CO2 emission problem, while the reported results often suffer a low energy conversion efficiency. In this paper, we report how metallic Cu was loaded on to TiO2 nanotube arrays by a chemical reduction – solar drying method, and it showed high activity and efficiency in the photothermal environment created by concentrating solar light. With outdoor solar light as the energy source, the maximum yield rate of the total hydrocarbons reaches several thousand of μmol g−1 h−1, including a large amount of C2 products such as 650.9 μmol g−1 h−1 C2H4, 240.2 μmol g−1 h−1 C2H6, and 59.4 μmol g−1 h−1 C2H2. The maximum solar to chemical energy efficiency reaches 0.20%. A carbene path for the CO2 photoreduction is then inferred based upon the products' distribution. According to Newton's Second Law, the reasons for such a high reaction rate are simplified into the contribution of the Cu cocatalyst and the strengthening of the concentrating light induced reaction conditions. The results indicate the advantages and potential of the concentrating technology in the CO2 photoreduction and catalyst preparation, and the deconvolution of the contribution provides a solution for the in depth understanding of photothermal catalysis.
{"title":"Preparation, activity and mechanism of a metallic Cu/TiO2 nanotube array catalyst by a fast solar drying method for photothermal CO2 reduction under concentrating light","authors":"Zekai Zhang, Wei Yan, Ying Wang, Guokai Cui, Hanfeng Lu","doi":"10.1039/d4cy00175c","DOIUrl":"https://doi.org/10.1039/d4cy00175c","url":null,"abstract":"Photocatalytic reduction of CO<small><sub>2</sub></small> with solar energy can realize a carbon cycle and ultimately this could solve the CO<small><sub>2</sub></small> emission problem, while the reported results often suffer a low energy conversion efficiency. In this paper, we report how metallic Cu was loaded on to TiO<small><sub>2</sub></small> nanotube arrays by a chemical reduction – solar drying method, and it showed high activity and efficiency in the photothermal environment created by concentrating solar light. With outdoor solar light as the energy source, the maximum yield rate of the total hydrocarbons reaches several thousand of μmol g<small><sup>−1</sup></small> h<small><sup>−1</sup></small>, including a large amount of C<small><sub>2</sub></small> products such as 650.9 μmol g<small><sup>−1</sup></small> h<small><sup>−1</sup></small> C<small><sub>2</sub></small>H<small><sub>4</sub></small>, 240.2 μmol g<small><sup>−1</sup></small> h<small><sup>−1</sup></small> C<small><sub>2</sub></small>H<small><sub>6</sub></small>, and 59.4 μmol g<small><sup>−1</sup></small> h<small><sup>−1</sup></small> C<small><sub>2</sub></small>H<small><sub>2</sub></small>. The maximum solar to chemical energy efficiency reaches 0.20%. A carbene path for the CO<small><sub>2</sub></small> photoreduction is then inferred based upon the products' distribution. According to Newton's Second Law, the reasons for such a high reaction rate are simplified into the contribution of the Cu cocatalyst and the strengthening of the concentrating light induced reaction conditions. The results indicate the advantages and potential of the concentrating technology in the CO<small><sub>2</sub></small> photoreduction and catalyst preparation, and the deconvolution of the contribution provides a solution for the in depth understanding of photothermal catalysis.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Modification of functionalized functional groups on catalyst surfaces is an effective strategy to modulate surface active sites, regulate carrier dynamics and hence deeply investigate the structure–activity relationships. Herein, graphitic carbon nitride (g-C3N4, abbreviated as CN) was selected as an ideal catalyst and subjected to a facile impregnation treatment with dilute hydrohalic acid (HX, X = F, Cl and Br) aqueous solution at room temperature of 25 °C to obtain halogen ion surface-modified CN (denoted as CN-X). Characterization by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectroscopy, and zeta potential (ζ) was used to systematically investigate the composition and structural information of CN-X catalysts. Impressively, the photocatalytic degradation performances of rhodamine B (RhB), phenol and hydroxyl radical (·OH) generation over CN-X were all significantly improved compared with that of pristine CN. The enhanced photocatalytic performance of CN-X can be attributed to the enhanced concentration of charge carriers, suppressed recombination and effective separation and transfer of charge carriers, which is validated by photoelectrochemical (PEC) measurements, surface photovoltage (SPV), and steady-state fluorescence (PL) and time-resolved fluorescence (TRPL) spectra. This work provides a facile surface modification strategy to promote carrier separation and transport of CN, which may be informative for solar energy conversion of other semiconductor materials.
{"title":"Halogen anions (F−, Cl−, Br−) modulated the localized microstructure of g-C3N4 to facilitate charge separation and transport and enhance photocatalytic activities","authors":"Xiaogang Liu, Mengyu Chen, Xin Zhang","doi":"10.1039/d4cy00643g","DOIUrl":"https://doi.org/10.1039/d4cy00643g","url":null,"abstract":"Modification of functionalized functional groups on catalyst surfaces is an effective strategy to modulate surface active sites, regulate carrier dynamics and hence deeply investigate the structure–activity relationships. Herein, graphitic carbon nitride (g-C<small><sub>3</sub></small>N<small><sub>4</sub></small>, abbreviated as CN) was selected as an ideal catalyst and subjected to a facile impregnation treatment with dilute hydrohalic acid (HX, X = F, Cl and Br) aqueous solution at room temperature of 25 °C to obtain halogen ion surface-modified CN (denoted as CN-X). Characterization by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectroscopy, and zeta potential (<em>ζ</em>) was used to systematically investigate the composition and structural information of CN-X catalysts. Impressively, the photocatalytic degradation performances of rhodamine B (RhB), phenol and hydroxyl radical (·OH) generation over CN-X were all significantly improved compared with that of pristine CN. The enhanced photocatalytic performance of CN-X can be attributed to the enhanced concentration of charge carriers, suppressed recombination and effective separation and transfer of charge carriers, which is validated by photoelectrochemical (PEC) measurements, surface photovoltage (SPV), and steady-state fluorescence (PL) and time-resolved fluorescence (TRPL) spectra. This work provides a facile surface modification strategy to promote carrier separation and transport of CN, which may be informative for solar energy conversion of other semiconductor materials.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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