NaH doped TiO_(2)as a high-performance catalyst for Mg/MgH_(2)cycling stability and room temperature absorption  

作　　者：Joshua Adedeji Bolarin Zhao Zhang Hujun Cao Zhi Li Teng He Ping Chen 

机构地区：[1]Dalian National Laboratory for Clean Energy,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian,P.R.China [2]University of Chinese Academy of Sciences,Beijing 100049,P.R.China [3]Shangdong Energy Group Co.,LTD.,No.10777,Jingshi Road,Jinan City,Shandong Province,250014,P.R.China [4]School of Material Science and Engineering,Xi'an Jiaotong University,Xi'an,Shaanxi Province,710049,P.R.China

出　　处：《Journal of Magnesium and Alloys》2023年第8期2740-2749,共10页镁合金学报（英文）

基　　金：The authors acknowledge the Project supported by the National Key R&D Program of China(2019YFE0103600,2018YFB1502101);the Key R&D Program of Shandong Province,China(2020CXGC010402);the National Natural Science Foundation of China(51801197);the Liaoning Revitalization Talents Program(XLYC2002076);the Dalian High-level Talents Program(2019RD09);the Youth Innovation Promotion Association CAS(2019189);K.C.Wong Education Foundation(GJTD-2018–06).

摘　　要：This paper presents the catalytic effect of NaH doped nanocrystalline TiO_(2)(designated as NaTiOxH)in the improvement of MgH_(2)hydrogen storage properties.The catalyst preparation involves ball milling NaH with TiO_(2)for 3 hr.The addition of 5 wt%NaTiOxH powder into MgH_(2)reduces its operating temperature to∼185℃,which is∼110℃lower than the additive-free as-milled MgH_(2).The composite remarkably desorbs∼7.2 wt%H_(2)within 15 min at∼290℃and reabsorbs∼4.5 wt%H_(2)in 45 min at room temperature under 50 bar H_(2).MgH_(2)dehydrogenation is activated at 57 kJ/mol by the catalyst.More importantly,the addition of 2.5 wt%NaTiOxH catalyst aids MgH_(2)to reversibly produce∼6.1 wt%H_(2)upon 100 cycles within 475 hr at 300℃.Microstructural investigation into the catalyzed MgH_(2)composite reveals a firm contact existing between NaTiOxH and MgH_(2)particles.Meanwhile,the NaTiOxH catalyst consists of catalytically active Ti_(3)O_(5),and“rod-like”Na_(2)Ti_(3)O_(7)species liberated in-situ during preparation;these active species could provide multiple hydrogen diffusion pathways for an improved MgH_(2)sorption process.Furthermore,the elemental characterization identifies the reduced valence states of titanium(Ti<4+)which show some sort of reversibility consistent with H_(2)insertion and removal.This phenomenon is believed to enhance the mobility of Mg/MgH_(2)electrons by the creation and elimination of oxygen vacancies in the defective(TiO_(2-x))catalyst.Our findings have therefore moved MgH_(2)closer to practical applications.

关 键 词：Magnesium hydride NaH doped nanocrystalline TiO_(2) Kinetics Room temperature absorption REVERSIBILITY 

分 类 号：TQ426[化学工程]