Novel photocatalytic activity of Cu@V co-doped TiO₂/PU for CO₂ reduction with H₂O vapor to produce solar fuels under visible light

Pham, Thanh-Dong,Lee, Byeong-Kyu Elsevier 2017 Journal of catalysis Vol.345 No.-

<P><B>Abstract</B></P> <P>In this study, Cu and V co-doped TiO<SUB>2</SUB> deposited on polyurethane (Cu@V-TiO<SUB>2</SUB>/PU) was synthesized as a catalyst for the reduction of CO<SUB>2</SUB> with H<SUB>2</SUB>O vapor to preferentially produce CH<SUB>4</SUB> as a valuable solar fuel under visible light. The Cu and V dopants defected into the TiO<SUB>2</SUB> lattice, leading to the formation of Ti<SUP>3+</SUP> and oxygen vacancies in the lattice. The Ti<SUP>3+</SUP> formed in the doped TiO<SUB>2</SUB> lattice created an intermediate band between the valence band and the conduction band of TiO<SUB>2</SUB>, leading to an increase in the electron–hole pair separation efficiency of TiO<SUB>2</SUB>. The oxygen vacancies existing on the surface of the photocatalyst could induce new adsorption sites to adsorb CO<SUB>2</SUB>. The generated electrons and holes reacted with the adsorbed CO<SUB>2</SUB> and with H<SUB>2</SUB>O vapor to produce CO and primarily CH<SUB>4</SUB>. Therefore, the Cu@V-TiO<SUB>2</SUB>/PU photocatalysts successfully utilized visible light as the energy source and H<SUB>2</SUB>O vapor as a reductant to reduce CO<SUB>2</SUB> to CO and CH<SUB>4</SUB>. The Cu@V-TiO<SUB>2</SUB>/PU photocatalysts also supplied sufficient electrons and holes for the selective reduction of CO<SUB>2</SUB> to CH<SUB>4</SUB> rather than CO. The 2Cu@4V-TiO<SUB>2</SUB>/PU photocatalyst, with Cu/TiO<SUB>2</SUB> and V/TiO<SUB>2</SUB> ratios of 2 and 4wt.%, respectively, exhibited the highest photocatalytic activity for CO<SUB>2</SUB> conversion into solar fuels. The production rates of CH<SUB>4</SUB> and CO produced from the CO<SUB>2</SUB> reduction by the 2Cu@4V-TiO<SUB>2</SUB>/PU photocatalyst under visible light were 933 and 588μmolg<SUP>−1</SUP> cat.h<SUP>−1</SUP>, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu and V co-doping formed Ti<SUP>3+</SUP> and oxy-vacancies in the TiO<SUB>2</SUB> lattice. </LI> <LI> The twin-metal co-doping enhanced the separation of TiO<SUB>2</SUB>’s electron–hole pairs. </LI> <LI> The formed Ti<SUP>3+</SUP> and oxy-vacancies enhanced both the adsorption and conversion of CO<SUB>2</SUB>. </LI> <LI> The Cu@V-TiO<SUB>2</SUB>/PU converted CO<SUB>2</SUB> into CH<SUB>4</SUB> and CO even under visible light. </LI> <LI> The optimal doping ratios of Cu/TiO<SUB>2</SUB> and V/TiO<SUB>2</SUB> were 2 and 4wt.%, respectively. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Co-doped MgGa2O4 결정 성장과 광학적 특성

강종욱,방태환 인문사회과학기술융합학회 2018 예술인문사회융합멀티미디어논문지 Vol.8 No.6

Co-doped MgGa2O4 결정은 solid-state sintering 방법으로 성장하였다. Co-doped MgGa2O4 결정을 성장하기 위해서 고순도의 MgO와 Ga2O3 분말를 사용하였으며, 불순물로 첨가한 Co는 1mol%가 되도록 하였다. 상온에서 1500℃까지 승온 영역을 갖는 고온 전기로를 이용하여 1350℃ 온도에서 Co-doped MgGa2O4 결정을 성장하였다. EDS(Energy Dispersive Spectrometer)와 XRD(X-ray diffraction) 측정을 통해서 Co-doped MgGa2O4 결정의 구조와 조성을 분석하였다. XRD 분석으로부터 성장된 Co-doped MgGa2O4 결정의 구조는 cubic 결정구조이며, 격자상수값 a = 8.289Å으로 주어졌다. 측정된 광흡수 스펙트럼의 기초흡수단으로부터 구한 Co-doped MgGa2O4 결정은 직접전이 에너지 밴드 갭의 형태를 보였다. 293K에서 측정된 직접전이형 광학적 에너지 간격 Eg = 4.703 eV로 주 어졌다. Co-doped MgGa2O4 결정의 광발광 스펙트럼은 293 K온도에서 600 ~ 800 nm 영역에서 측정하여, Co2+ 이온에 기인한 광발광 스펙트럼이 689.8 nm 영역에서 관측되었다. Co-doped MgGa2O4 crystal was grown by solid-state sintering method. Growth of the Co-doped MgGa2O4 crystalline crystal was achieved by employing high-purity MgO and Ga2O3 powders, and the Co added as impurities was 1 mol%. Co-doped MgGa2O4 crystal growth was to use a high-temperature electric furnace having a temperature rising region from room temperature to 1500 ℃, was grown at 1350 ℃. The structure and composition of Co-doped MgGa2O4 crystals were analyzed by EDS (Energy Dispersive Spectrometer) and XRD (X-ray diffraction) measurements. XRD analysis revealed that Co-doped MgGa2O4 crystal adopt a cubic structure with respective lattice constants of a = 8.289 Å. The optical absorption spectrum obtained near the fundamental absorption edge showed that this compound has a direct energy band gap. The direct optical energy gap of the Co-doped MgGa2O4 crystal was given as Eg = 4.703 eV, respectively, at 293 K. The PL(Photoluminescence) spectrum of the Co-doped MgGa2O4 crystal was measured wavelength range 600 ~ 800 nm at 293 K, and a high intensity emission peak due to the Co2+ ion.

Novel capture and photocatalytic conversion of CO₂ into solar fuels by metals co-doped TiO₂ deposited on PU under visible light

Pham, Thanh-Dong,Lee, Byeong- Kyu Elsevier 2017 Applied Catalysis A Vol.529 No.-

<P><B>Abstract</B></P> <P>In this study, Ag and Cu co-doped TiO<SUB>2</SUB> deposited on polyurethane (Ag@Cu-TiO<SUB>2</SUB>/PU) was synthesized for the conversion of CO<SUB>2</SUB> into solar fuels under visible light. The synthesized Ag@Cu-TiO<SUB>2</SUB>/PU, which synergistically inherited all the advantages of both Ag and Cu doping, exhibited very high photocatalytic activity for the reduction of gaseous CO<SUB>2</SUB> to produce CH<SUB>4</SUB> and CO fuels. The dopants defects in the TiO<SUB>2</SUB> lattice formed Ti<SUP>3+</SUP> and oxygen vacancies in the lattice. The presence of Ti<SUP>3+</SUP> and oxygen vacancies on the surface of the photocatalyst induced the formation of new adsorption sites to adsorb CO<SUB>2</SUB>. The Ag and Cu dopants also enhanced the separation of electron–hole pairs of the doped TiO<SUB>2</SUB> photocatalysts. Therefore, the Ag@Cu- TiO<SUB>2</SUB>/PU photocatalysts generated electron–hole pairs, which could react with H<SUB>2</SUB>O and CO<SUB>2</SUB> to produce the CO and CH<SUB>4</SUB>, even under visible light. 2Ag@4Cu-TiO<SUB>2</SUB>/PU, corresponding to the Ag/TiO<SUB>2</SUB> and Cu/TiO<SUB>2</SUB> ratios of 2 and 4wt%, respectively, exhibited the highest photocatalytic reduction of CO<SUB>2</SUB>. The yields of CH<SUB>4</SUB> and CO produced from the photocatalytic reduction of CO<SUB>2</SUB> by 2Ag@4Cu-TiO<SUB>2</SUB>/PU under visible light were 880 and 550 (μmol/g.cat), respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ag and Cu co-doping formed Ti<SUP>3+</SUP> and oxy-vacancies in the TiO<SUB>2</SUB> lattice. </LI> <LI> The formed Ti<SUP>3+</SUP> and oxy-vacancies enhanced both the CO<SUB>2</SUB> adsorption and conversion. </LI> <LI> Ag and Cu co-doping also enhanced the separation of electron–hole pairs of the TiO<SUB>2</SUB>. </LI> <LI> Ag@Cu-TiO<SUB>2</SUB>/PU converted CO<SUB>2</SUB> into CH<SUB>4</SUB> and CO even under visible light. </LI> <LI> The optimal doping ratios of Ag/TiO<SUB>2</SUB> and Cu/TiO<SUB>2</SUB> were 2 and 4wt%, respectively. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Nitrogen‑doped nanoporous carbons derived from lignin for high CO2 capacity

Sohyun Park,Min Sung Choi,Ho Seok Park 한국탄소학회 2019 Carbon Letters Vol.29 No.3

In this paper, nitrogen (N)-doped ultra-porous carbon derived from lignin is synthesized through hydrothermal carbonization, KOH activation, and post-doping process for CO2 adsorption. The specific surface areas of obtained N-doped porous carbons range from 247 to 3064 m2/g due to a successful KOH activation. N-containing groups of 0.62–1.17 wt% including pyridinic N, pyridone N, pyridine-N-oxide are found on the surface of porous carbon. N-doped porous carbon achieves the maximum CO2 adsorption capacity of 13.6 mmol/g at 25 °C up to 10 atm and high stability over 10 adsorption/desorption cycles. As confirmed by enthalpy calculation with the Clausius–Clapeyron equation, an adsorption heat of N-doped porous carbon is higher than non-doped porous carbon, indicating a role of N functionalities for enhanced CO2 adsorption capability. The overall results suggest that this carbon has high CO2 capture capacity and can be easily regenerated and reused without any clear loss of CO2 adsorption capacity.

분무열분해법으로 성장한 Co-, Fe-doped TiO2 박막의 구조와 광학적 특성

최성휴,강동완,서동주 한국물리학회 2008 새물리 Vol.56 No.5

Co- and Fe-doped TiO$_2$ films were deposited the glass substrates by using spray pyrolysis. The structural properties of the films were studied using X-ray diffraction (XRD), Spell out (SEM), and Spell out (EDS). The Co- and Fe-doped TiO$_2$ films prepared at a substrate temperature of 450 $^\circ$C were identified as having the tetragonal structure of TiO$_2$ films with a (101) preferred orientation. The XRD analysis revealed that the Co- and the Fe-doped TiO$_2$ films had a tetragonal structure. The optical absorption spectra obtained near the fundamental absorption edge showed that these compounds had a direct energy band gaps. The direct energy gaps of Co-doped TiO$_2$ films (prepared at 450 $^\circ$C)and Fe-doped TiO$_2$ films (prepared at 450$^\circ$C and post-annealed at 600 $^\circ$C in the air for 2 hours) at 298 K were 3.656 eV and 3.665 eV, respectively. $3d$ 전이원소인 코발트와 철을 불순물로 첨가시킨 Co-, Fe-doped TiO$_2$ 박막을 분무열분해법으로 유리기판위에 450$^\circ$C온도에서 성장하였다. 성장된 박막을 600 $^\circ$C에서 2시간 동안 공기 중에서 열처리 후 결정구조와 표면형태와 미세구조를 조사하였고, 시료에 대한 박막의 광흡수 스펙트럼을 측정하여 광학적 에너지 띠 간격을 구하였다. 열처리한 Co-, Fe-doped TiO$_2$ 박막은 (101), (004), (002) 면이 성장된 다결정 박막이었으며, tetragonal 구조이고, 격자상수는 $a_0$ = 3.873 ${\AA}$, $c_0$ = 3.873 ${\AA}$과 $a_0$ = 3.873 ${\AA}$, $c_0$ = 3.873 ${\AA}$이었다. 기초 흡수단 영역에 측정한 Co-, Fe-doped TiO$_2$ 박막은 직접전이 밴드 구조이고, 339 nm, 338 nm 영역에서 광흡수 증가가 나타났으며, 광학적 에너지 간격은 3.656 eV 와 3.665 eV이었다.

Facial Synthesized Co-doped SnO2@Multi-Walled Carbon Nanotubes as an Efficient Microwave Absorber in High Frequency Range

Zhenfeng Liu,Honglong Xing,Ling Lin,Xiaoli Ji,Ziyao Shen 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.10

Co-doped SnO2@multi-walled carbon nanotubes (MWCNTs) were fabricated by a one-pot hydrothermal process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high-resolution electron microscopy, and X-ray photoelectron spectroscopy (XPS) were employed to characterize the morphology and structure of the composites. XRD, FT-IR, and XPS analyses demonstrated that Co was doped into SnO2 lattice, no other impure phases were detected. Co-doped SnO2, with a uniform size of 4–6 nm, is coated on MWCNTs but separated from the nanotubes with some aggregation. The microwave absorption properties of Co-doped SnO2@MWCNTs were investigated at room temperature within 2–18 GHz. Results indicated that Co-doping concentration plays an important role in the microwave absorption capability of Co-doped SnO2@MWCNTs. The maximum reflection loss (RL) is 22.8 dB at 14.1 GHz. The absorption bandwidth with RL less than 10 dB is 4.2 GHz (12.2–16.4) with coating thickness of only 1.5 mm; hence, Co-doping can enhance the microwave absorption performance of SnO2@MWCNTs. The excellent microwave absorption performance may be attributed to interfacial polarization, conductivity loss, and changes in electromagnetic parameters and lattice constant caused by Co-doping. Consequently, Co-doped SnO2@MWCNTs can be considered as efficient microwave absorbers in high-frequency range.

La와 Co를 첨가한 BiFeO₃박막의 구조와 전기적 특성

김은선,김진원,도달현,김상수 한국물리학회 2011 새물리 Vol.61 No.4

We prepared 300-nm-thick pure BiFeO₃and La- and Co-doped BiFeO₃(Bi_(0.9)La_(0.1)FeO₃,Bi(Fe_(0.975)Co_(0.025)O_3-δ and (Bi_(0.9)La_(0.1)) (Fe_(0.975)Co_(0.025))O_3-δ thin films on Pt(111)/Ti/SiO₂/Si (100) substrates by using a chemical solution deposition method. The thin films were annealed at 550℃ for 30 min by using a conventional annealing process under a nitrogen atmosphere. The crystal structure and the surface microstructure of the thin films were investigated by using X-ray diffraction, scanning electron microscopy and Raman spectroscopy. The remnant polarization (2P_r)and the coercive field (2E_c) of the (Bi_(0.9)La_(0.1)) (Fe_(0.975)Co_(0.025))O_3-δ thin film were 95 μC/cm² and 925 kV/cm, respectively, at an applied electric field of 1326 kV/cm. The leakage current density of the thin films was improved compared to that of pure BiFeO₃. The good ferroelectric properties observed in the La- and the Co-doped BiFeO₃ thin films may be related to a reduction in the numbers of bismuth vacancies and oxygen vacancies. 화학 용액 증착법으로 300 nm두께의 순수한 BiFeO₃박막과 BiFeO₃의Bi^(3+)와 Fe^(3+)이온 일부를 La^(3+), Co^(3+) 이온으로치환한 (Bi_(0.9)La_(0.1)FeO₃,Bi(Fe_(0.975)Co_(0.025)O_3-δ,(Bi_(0.9)La_(0.1)) (Fe_(0.975)Co_(0.025))O_3-δ박막을 Pt(111)/Ti/SiO₂/Si(100)기판 위에 성장시켜 이들 박막의구조와 전기적 특성을 측정, 비교 분석하였다. 성장된 박막은 550℃의 질소 분위기에서 통상적인 방법으로 열처리 하였으며 이박막의 결정화 상태와 미세구조는 X-선 회절 실험과 라만 분광스펙트럼,주사 전자 현미경 측정 결과로부터 알아 보았다. 특히 La와 Co로 동시에치환시킨(Bi_(0.9)La_(0.1)) (Fe_(0.975)Co_(0.025))O_3-δ박막이 순수한 BiFeO₃박막에 비해 향상된 전기적 특성을 보였다. 이박막은 잘 정의된 전기 분극-전기장(P-E) 이력곡선을 보였으며 1326kV/cm의 전기장에서 잔류 분극 값(2P_r) 및 항 전기장 값(2E_c)은각각 95μC/cm², 925 kV/cm으로 측정되었다. 또 누설 전류 밀도역시 순수한 BiFeO₃박막에 비해 향상되었음을 확인할 수 있었다. 이박막이 좋은 전기적 특성을 보이는 것은 La와 Co치환에 의해 비스무스휘발에 의한 비스무스 빈자리나 산소 빈자리의 감소가 일어났기때문이라고 보여진다.

Co가 도핑된 ZnO 나노입자의 Zn/Co ZIF 유도 합성 및 고성능 트리메틸아민 센서로의 응용

윤지욱 한국결정성장학회 2018 한국결정성장학회지 Vol.28 No.5

Zn1 − xCox Zeolitic Imidazolate Framework-8(ZIF)(x = 0~0.05)를 2-methylimidazole을 사용하여 Zn 2+와 Co 2+를 공침시켜 합성하고, 이를 600 o C에서 2시간 열처리하여 순수한 ZnO 나노입자와 Co가 도핑된 ZnO 나노입자를 합성했다. x가< 0.05일 경우, 2-methylimidazole 링커가 Zn 2+ 및 Co 2+ 모두에 강하게 배향되어 균질한 Zn/Co ZIFs가 합성되었으며, 열처리를 통해 Co가 균일하게 도핑된 ZnO를 합성할 수 있었다. 반면, x ≥ 0.05일 때는 불균질한 Zn/Co ZIFs가 합성되었으며, 열처리 이후 Co3O4 이차상이 형성되었다. 합성된 나노입자들에 대한 가스감응특성 평가 결과, 3 at%의 Co가 도핑된 ZnO 센서는 순수한 ZnO와는 달리 trimethylamine에 대해 고감도, 고선택적 가스감응특성을 나타냈다. 본 연구의 bimetallic ZIF 유도산화물 나노복합체 합성방법은 고성능 가스센서를 설계하는데 활용될 수 있을 것으로 기대된다. Zn1 − xCox Zeolitic Imidazolate Framework (ZIF) (x = 0~0.05) were prepared by the co-precipitation of Zn 2+ and Co 2+ using 2-methylimidazole, which were converted into pure and Co-doped ZnO nanoparticles by heat treatment at 600 o C for 2 h. Homogeneous Zn/Co ZIFs were achieved at x < 0.05 owing to the strong coordination of the imidazole linker to Zn 2+ and Co 2+ , facilitating atomic-scale doping of Co into ZnO via annealing. By contrast, heterogeneous Zn/Co ZIFs were formed at x ≥ 0.05, resulting in the formation of Co3O4 second phase. To investigate the potential as high-performance gas sensors, the gas sensing characteristics of pure and Co-doped ZnO nanoparticles were evaluated. The sensor using 3 at% Co-doped ZnO exhibited an unprecedentedly high response and selectivity to trimethylamine, whereas pure ZnO nanoparticles did not. The facile, bimetallic ZIF derived synthesis of doped-metal oxide nanoparticles can be used to design high-performance gas sensors.

N₂O 분해반응용 Co₃O₄ 기반 촉매의 K첨가 효과

황라현(Ra Hyun Hwang),박지혜(Ji Hye Park),백정훈(Jeong Hun Baek),임효빈(Hyo Been Im),이광복(Kwang Bok Yi) 한국청정기술학회 2018 청정기술 Vol.24 No.1

N₂O 촉매 분해 반응을 위한 Co₃O₄ 촉매는 공침법을 이용하여 제조하였으며, 조촉매로서 Ce 및 Zr의 양을 (Ce 또는 Zr)/Co = 0.05의 몰비로 고정하여 제조하였다. 또한 K가 촉매에 미치는 영향을 조사하기 위해 1 wt%의 K₂CO₃를 함침하여 촉매를 제조하였다. 제조된 촉매의 특성은 BET, SEM, XRD, H₂-TPR, XPS를 통해 분석하였다. Co₃O₄ 촉매는 스피넬 결정상을 나타냈으며, 조촉매의 첨가는 입자 크기와 결정 크기를 감소시켜 비표면적을 증가시키는 것으로 나타났다. K의 도핑은 촉매 활성물질인 Co의 활성 종인 Co<SUP>2+</SUP>의 농도를 증가시켜 촉매 활성을 향상시키는 것으로 확인되었다. N₂O 분해 반응 테스트는 GHSV = 45,000 h-1, 250 ~ 375 ℃에서 수행되었으며 Co₃O₄ 촉매에 조촉매를 첨가하였을 때도 반응성이 증가하였지만, K를 함침하면 활성이 더욱 크게 증가하는 것으로 나타났다. K의 도핑이 활성 종인 Co<SUP>2+</SUP>의 농도를 증가시키며, 환원온도를 낮춰주어 활성에 큰 영향을 주는 것으로 확인하였다. Co₃O₄ catalysts for N₂O decomposition were prepared by co-precipitation method. Ce and Zr were added during the preparation of the catalyst as promoter with the molar ratio (Ce or Zr) / Co = 0.05. Also, 1 wt% K₂CO₃ was doped to the prepared catalyst with impregnation method to investigate the effect of K on the catalyst performance. The prepared catalysts were characterized with SEM, BET, XRD, XPS and H₂-TPR. The Co₃O₄ catalyst exhibited a spinel crystal phase, and the addition of the promoter increased the specific surface area and reduced the particle and crystal size. It was confirmed that the doping of K improves the catalytic activity by increasing the concentration of Co<SUP>2+</SUP> in the catalyst which is an active site for catalytic reaction. The catalytic activity tests were carried out at a GHSV of 45,000 h-1 and a temperature range of 250 ~ 375 ℃. The K-impregnated Co₃O₄ catalyst showed much higher activity than Co₃O₄ catalysts with promoter only. It is found that the K-impregnation increased the concentration of Co<SUP>2+</SUP> more than the added of promoter did, and lowered the reduction temperature to a great extent.

Facile synthesis of hierarchically porous MgO sorbent doped with CaCO₃ for fast CO₂ capture in rapid intermediate temperature swing sorption

Jin, Seongmin,Ho, Keon,Lee, Chang-Ha Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.334 No.-

<P><B>Abstract</B></P> <P>For CO<SUB>2</SUB> sorbents, a fast sorption rate is as important as the sorption capacity in order to enable efficient CO<SUB>2</SUB> capture in the treatment of large amounts of emission gas, where the contact time between the sorbent and gas is limited. A facile and environmentally benign method of fabricating advanced sorbents with fast CO<SUB>2</SUB> sorption for pre-combustion capture was developed by incorporating CaCO<SUB>3</SUB> into triple salt-promoted MgO sorbents (LiNO<SUB>3</SUB>, NaNO<SUB>3</SUB>, and Na<SUB>2</SUB>CO<SUB>3</SUB>) using salt-controllable coprecipitation. The incorporation of Ca into the salt-promoted MgO (MgCa) was effective for controlling the lattice parameter, textural properties, and basicity. The salt-promoted MgCa sorbents had a bi-disperse pore distribution with different range, which contributed to the fast sorption. When 5 mol.% of Ca was doped into the triple salt-promoted MgO, the CO<SUB>2</SUB> sorption capacity within 10 min was significantly improved (from 6 wt% (MgO) to 43 wt% (MgCa-5%)) at 325 °C. For CO<SUB>2</SUB> sorption for 10 min at 325 °C and N<SUB>2</SUB> regeneration for 5 min at 400 °C, the working capacity of MgCa-5% was approximately 30 wt% at the 30 th cycle. Under the same rapid cycling conditions, the sorption capacity was 12 wt% when a wet CO<SUB>2</SUB> mixture (29 vol% CO<SUB>2</SUB>, 3 vol% H<SUB>2</SUB>O, and balance N<SUB>2</SUB>) and pure CO<SUB>2</SUB> was used for sorption and regeneration, respectively. When the regeneration gas contained water vapour, the cyclic sorption capacity decreased to 1–2 wt%. The MgCa sorbents prepared via salt-controllable coprecipitation exhibited high working capacities during the rapid cyclic temperature swing operation at intermediate temperature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Doping of CaCO<SUB>3</SUB> controlled the mesopore and lattice parameter of MgO composites. </LI> <LI> The composites showed an enhanced CO<SUB>2</SUB> sorption rate at intermediate temperatures. </LI> <LI> Well-developed mesopores with 5–30 nm accelerated the sorption rate within 10 min. </LI> <LI> The regeneration temperature decreased in the presence of water vapor by 10 °C. </LI> <LI> CaCO<SUB>3</SUB> doping led to 3-fold increased capacity in rapid temperature swing sorption. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>