工程科学学报2026，Vol.48Issue(9)：2003-2013,11.DOI:10.13374/j.issn2095-9389.2026.01.09.002
Pt-Mg-MOF-74-R的开放金属位点微环境调控及其储氢性能研究
Research on the microenvironment regulation of open metal sites and hydrogen storage performance of Pt-Mg-MOF-74-R
摘要
Abstract
Metal-organic frameworks(MOFs)hold great promise for hydrogen storage owing to their high specific surface areas,tunable pore structures,and chemical modifiability.Mg-MOF-74 has attracted considerable attention because of its unique structural features:Mg ions coordinate with five oxygen atoms and one solvent molecule,and open metal sites(OMSs)are generated upon activation to remove the solvent.This material possesses a highly polarized pore environment,offering inherent potential for hydrogen storage.However,existing studies have shown that the hydrogen uptake of Mg-MOF-74 remains below 0.15%weight present at 298 K and 7 MPa,and its practical application is severely limited by sluggish H2 diffusion kinetics.Introducing noble metal components can trigger the hydrogen spillover effect,in which H2 molecules dissociate into H atoms and migrate to the support,significantly enhancing the storage capacity.To address the insufficient adsorption sites and stability issues of MOF-based hydrogen storage materials,a series of Pt-Mg-MOF-74-R composites with varying Pt loadings and defect levels were fabricated via in situ Pt introduction using K2PtCl4 as t he Pt source,followed by thermal reduction in an Ar/H2 atmosphere with Mg-MOF-74 as the host.Systematic characterization by XRD,FT-IR spectroscopy,SEM,TGA,TEM,and XPS revealed the effects of the reduction temperature and Pt loading on the framework defect formation and metal valence states.The thermal reduction process effectively reduced the Pt ions to highly active Pt0 nanoparticles while removing solvent molecules and inducing partial ligand loss,leading to the construction of abundant MgO5 open metal sites.The FT-IR results showed that the Pt-loaded materials exhibited peak positions similar to those of pristine Mg-MOF-74,with no new functional groups detected,indicating that Pt was predominantly present in a physically loaded state within the n-Pt-Mg-MOF-74 framework.Hydrogen storage tests showed that 4-Pt-Mg-MOF-74-R200 achieved a gravimetric uptake of 0.35%weight present at 298 K and 10 MPa,which was 2.5 times that of pristine Mg-MOF-74 under identical conditions.The adsorption enthalpy reached-22.35 kJ·mol-1,3.8 times higher than that of the original Mg-MOF-74,with the thermal reduction process playing a key role.Mechanistic analyses indicated that thermal reduction increased the content of well-dispersed Pt0,facilitating hydrogen spillover by dissociating H2 molecules into H atoms.Simultaneously,thermal reduction removed linkers without collapsing the framework,increasing the number of MgO5 open metal sites available for hydrogen binding and optimizing the mass transfer pathways and coordination environment,thereby providing more transport routes and adsorption sites for the H atoms generated via spillover.The two mechanisms reinforce one another and collectively enhance the room-temperature hydrogen storage capacity of 4-Pt-Mg-MOF-74-R200.Notably,increasing the reduction temperature from 200℃to 300℃caused partial pore collapse,a decrease in the specific surface area,and a significant increase in the mesoporosity.These structural changes adversely affected the hydrogen storage performance,with 4-Pt-Mg-MOF-74-R200 clearly outperforming 4-Pt-Mg-MOF-74-R300.Although thermal reduction generates highly active defect sites that substantially enhance the hydrogen adsorption capacity,excessive temperatures compromise the pore architecture.The balance between defect engineering and structural integrity indicates that an optimal reduction temperature of 200℃maximizes the hydrogen storage performance by preserving an adequate pore structure and surface area while optimizing the quantity and distribution of defect sites.This study primarily reveals the synergistic mechanism of"hydrogen spillover+defect sites"in MOF-based hydrogen storage.关键词
金属有机框架/贵金属负载/储氢材料/氢溢流效应/开放金属位点/热还原Key words
metal-organic framework/noble metal loading/hydrogen storage material/hydrogen spillover effect/open metal site/thermal reduction分类
通用工业技术引用本文复制引用
何涛,左佳一,王浩..Pt-Mg-MOF-74-R的开放金属位点微环境调控及其储氢性能研究[J].工程科学学报,2026,48(9):2003-2013,11.基金项目
国家自然科学基金青年基金(51702013) （51702013）
国家能源石油炼制技术研发中心开放基金课题(36800000-23-ZC0613-0007) （36800000-23-ZC0613-0007）
北京市自然科学基金-小米创新联合基金(L233011) （L233011）
