Systematic study of H2 production from catalytic photoreforming of cellulose over Pt catalysts supported on TiO2

Hydrogen (H₂) production from photocatalytic reforming of cellulose is a promising way for sustainable H₂ to be generated. Herein, we report a systematic study of the photocatalytic reforming of cellulose over Pt/m-TiO₂ (i.e. mixed TiO₂, 80% of anatase and 20% of rutile) catalysts in water. The optimum operation condition was established by studying the effect of Pt loading, catalyst concentration, cellulose concentration and reaction temperature on the gas production rate of H₂ (r_H2) and CO₂ (r_CO2), suggesting an optimum operation condition at 40 ℃ with 1.0 g·L^-1 of cellulose and 0.75 g·L^-1 of 0.16-Pt/m-TiO₂ catalyst (with 0.16 wt% Pt loadting) to achieve a relatively sound photocatalytic performance with rH₂ = 9.95 μmol·h^-1. It is also shown that although the photoreforming of cellulose was operated at a relatively mild condition (i.e. with an UV-A lamp irradiation at 40 ℃ in the aqueous system), a low loading of Pt at ~0.16 wt% on m-TiO₂ could promote the H₂ production effectively. Additionally, by comparing the reaction order expressed from both r_H2 (a₁) and rCO₂ (a₂) with respect to cellulose and water, the possible mechanism of H₂ production was proposed.     

Simultaneous oxidative conversion and CO2 or steam reforming of methane to syngas over CoO–NiO–MgO catalyst

CO₂ reforming, oxidative conversion and simultaneous oxidative conversion and CO₂ or steam reforming of methane to syngas (CO and H₂) over NiO–CoO–MgO (Co: Ni: Mg=0·5: 0·5:1·0) solid solution at 700–850°C and high space velocity (5·1×10⁵ cm³ g⁻¹ h⁻¹ for oxidative conversion and 4·5×10⁴ cm³ g⁻¹ h⁻¹ for oxy-steam or oxy-CO₂ reforming) for different CH₄/O₂ (1·8–8·0) and CH₄/CO₂ or H₂O (1·5–8·4) ratios have been thoroughly investigated. Because of the replacement of 50 mol% of the NiO by CoO in NiO–MgO (Ni/Mg=1·0), the performance of the catalyst in the methane to syngas conversion process is improved; the carbon formation on the catalyst is drastically reduced. The CoO–NiO–MgO catalyst shows high methane conversion activity (methane conversion >80%) and high selectivity for both CO and H₂ in the oxy-CO₂ reforming and oxy-steam reforming processes at ⩾800°C. The oxy-steam or CO₂ reforming process involves the coupling of the exothermic oxidative conversion and endothermic CO₂ or steam reforming reactions, making these processes highly energy efficient and also safe to operate. These processes can be made thermoneutral or mildly exothermic or mildly endothermic by manipulating the process conditions (viz. temperature and/or CH₄/O₂ ratio in the feed). © 1998 Society of Chemistry Industry     

Renewable hydrogen production from steam reforming of glycerol (SRG) over ceria-modified γ-alumina supported Ni catalyst

Excess crude glycerol derived as a by-product from biodiesel industry prompts the need to valorise glycerol to value-added chemicals. In this context, catalytic steam reforming of glycerol (SRG) was proposed as a promising and sustainable alternative for producing renewable hydrogen (H₂). Herein, the development of nickel (Ni) supported on ceria-modified mesoporous γ-alumina (γ-Al₂O₃) catalysts and their applications in catalytic SRG (at 550–750 °C, atmospheric pressure and weight hourly space velocity, WHSV, of 44,122 ml·g⁻¹·h⁻¹ (STP)) is presented. Properties of the developed catalysts were characterised using many techniques. The findings show that ceria modification improved Ni dispersion on γ-Al₂O₃ catalyst support with highly active small Ni particles, which led to a remarkable catalytic performance with the total glycerol conversion (ca. 99%), glycerol conversion into gaseous products (ca. 77%) and H₂ yield (ca. 62%). The formation rate for H₂ production (14.4 × 10⁻⁵ mol·s⁻¹·g⁻¹, TOF (H₂) = 3412 s⁻¹) was significantly improved with the Ni@12Ce-Al₂O₃ catalyst, representing nearly a 2-fold increase compared with that of the conventional Ni@Al₂O₃ catalyst. In addition, the developed catalyst also exhibited comparatively high stability (for 12 h) and coke resistance ability.     

Chlorination of Pt–Re/Al2O3 during naphtha reforming

The reforming of a paraffinic naphtha was studied in order to determine the influence of chlorination during the run. Experiments were performed at 505°C, 15 kg cm⁻², WHSV = 4, H₂: HC= 4, and with or without an 8 h initial period of deactivation at 1 kg cm⁻². A commercial Pt–Re/Al₂O₃ (0·3% Pt, 0·3% Re, 0·04% S, 0·15% Cl) catalyst was chlorinated using naphtha feeds with different H₂O/Cl ratios. A model of the chlorination kinetics was developed and represents adequately the experimental results. The acid controlled reactions such as C₂–C₄ and production of C₅ paraffins, disappearance of C₉ paraffins and production of aromatics increase in parallel to the chlorination of the catalyst and the increase is independent of the amount of coke deposited on the catalyst. The sites of chlorine adsorption are different from the sites of coke deposition.     

Silver/Platinum Supported on TiO<Subscript>2</Subscript> P25 Nanocatalysts for Non-photocatalytic and Photocatalytic Denitration of Water

Denitration of water was investigated by non-photocatalytic and/or photocatalytic processes (UV-A irradiation at 365 nm) using a mixture of Ag/P25?+?Pt/P25 monometallic catalysts and Ag–Pt(Pt–Ag)/P25 bimetallic catalysts (2 wt% Ag; 4 wt% Pt) prepared by drop-wise wetness impregnation of TiO₂ P25 support. In the bimetallic samples, the influences of the Pt precursor (H₂PtCl₆·6H₂O; K₂PtCl₆) and of the impregnation order of the metallic salts were examined. The highest N₂ yield (42.3%) in the non-photocatalytic process was achieved with the Ag/P25?+?Pt/P25 mixture but with ca. 12.6% NO₂ ^? yield. Photocatalytic activity was enhanced in presence of H₂ in comparison to H₂-free condition. Ag/P25 is the most active photocatalyst, however high NO₂ ^? yield is obtained (32.5%). The bimetallic samples exhibit high versatility, being active both in the non-photocatalytic and the photocatalytic processes. Low NO₃ ^? conversion and high NO₂ ^? selectivity results were obtained from impregnation of Ag first. In contrast, impregnation of Pt precursor from K₂PtCl₆ first effectively promoted NO₃ ^? reduction towards N₂ yield of 36% and particularly low NO₂ ^? yield of 2.7%, due the presence of metallic nanoparticles of different sizes and interaction with TiO₂ with a peculiar strong Pt and Ag interaction. Best results obtained in non-photocatalytic and photocatalytic processes are almost similar.     

Transition metal α-carbonyl diazoalkane coordination chemistry: structures derived from a side-on diazomalonate platinum complex

The labile side-on α-carbonyl diazoalkane platinum complex (dtbpm-κ²P)Pt[N₂C(CO₂Me)₂-κ²N,N′] (2) displays nucleophilic as well as electrophilic reactivity patterns. H₂O is added stoichiometrically, forming the hydrazonido hydroxo platinum(II) complex (dtbpm-κ²P)Pt(OH)[NHNC(CO₂Me)₂] (3). Protonation of 2 with BF₃·OEt₂ and MeOH yields [(dtbpm-κ²P)Pt{NHNC(CO₂Me)₂-κN,κO}]⁺[BF₄]⁻ ([4]⁺[BF₄]⁻). Both new complexes have been fully characterized spectroscopically and by single crystal X-ray diffraction.     

X-ray single-crystal structure and magnetic properties of KMn(H2O)5Ru2(CO3)4·5H2O: A layered soft magnet

The temperature manipulation induces the aggregation of Ru₂(CO₃)₄^3 − paddle-wheel precursors and Mn^2 + ions in lower temperature ~ 10 °C forming layer structural complex, K[Mn(H₂O)₄Ru₂(CO₃)₄]·5H₂O (1). It composes of new negative layer {Mn(H₂O)₅Ru₂(CO₃)₄}_nⁿ⁻, and magnetic exchanges between spin centers result in ordering below 3.8 K. The observed critical temperature is like the previously reported 3D hetero-metallic carbonates H_0.3K_0.7Mn[Ru₂(CO₃)₄](H₂O)_5.5, which demonstrates that it is independent of the interlayer connecting in such heterometallic complexes based on square-grid layer {Ru₂(CO₃)₄}_n³ⁿ⁻.     

Cu3P and Ni2P co-modified g-C3N4 nanosheet with excellent photocatalytic H2 evolution activities

Copper-nickel phosphides/ graphite-like phase carbon nitride (Cu₃P-Ni₂P/g-C₃N₄) composites were obtained through a facile one-pot in situ solvothermal approach. The coexistence of Cu₃P and Ni₂P plays an important role in enhancing the catalytic activity of g-C₃N₄. The 7 wt% Cu₃P-Ni₂P/g-C₃N₄ bimetallic phosphide photocatalyst demonstrates the best photocatalytic hydrogen (H₂) evolution rate of 6529.8 μmol g⁻¹ h⁻¹, which is 80.7-fold higher than that of g-C₃N₄. The apparent quantum yield (AQE) was determined to be 18.5% at 400 nm over the 7% Cu₃P-Ni₂P/g-C₃N₄. This in situ growth strategy produced intimate contact interfaces, leading to a significantly promoted separation of charge carriers, and hence strengthened the photocatalytic H₂ production. Moreover, the coexistence of Cu₃P and Ni₂P reduced the overpotential of H₂ during the evolution process, further benefiting H₂ production. Finally, the photocatalytic enhancement mechanism was proposed and verified by fluorescence and electrochemical analysis. This work provides a low-cost strategy to synthesize nonprecious bimetallic phosphides/carbon nitride photocatalyst with outstanding H₂ production activity. © 2020 Society of Chemical Industry     

Carbon nano-layer coated TiO2 nanoparticles for efficient photocatalytic CO2 reduction into CH4 and CO

Solar-driven photocatalytic reduction of CO₂ into value-added fuel is an exciting concept that can address serious global challenges such as greenhouse effect and energy crisis. However, the low sunlight utilization by the photocatalysts and their high production costs have greatly hindered their mass adoption. Herein, we proposed a facile and efficient approach to prepare the carbon nano-layer coated TiO₂ as an efficient photocatalyst for the photocatalytic reduction of CO₂ into CH₄ and CO. By pyrolyzing linear low-density polyethylene, a carbon nano-layer was formed on the surface of TiO₂. The obtained carbon nano-layer coated TiO₂ was able to exhibit superior photocatalytic CO₂ reduction activity as compared to its unmodified counterpart, whereby, a CH₄ production rate of ~2.30 μmol · g⁻¹ h⁻¹ was achieved (prepared at a dwelling temperature of 600 °C). Meanwhile, a CO production rate of ~16.76 μmol · g⁻¹ h⁻¹ was recorded for the materials prepared at a dwelling temperature of 500 °C. The enhanced CH₄ and CO production can be attributed to the elevated absorbance in the visible-light region, decreased band gap and effective restriction of photogenerated electron-hole pair recombination. Thus, based on the results, carbon nano-layer coated TiO₂ can be a promising alternative for the photocatalytic reduction of CO₂ into valuable fuel for large-scale application.     

Synthesis and characterization of ternary layered i-MAX (Mo2/3Y1/3)2AlC ceramics fabricated by spark plasma sintering

In this paper, the i-MAX phase (Mo_2/3Y_1/3)₂AlC ceramic with high purity of 98.29 wt% (1.13 wt% Y₂O₃ and 0.58 wt% Mo₂C) and high relative density of 98.59% was successfully synthesized by spark plasma sintering (SPS) at 1500°C with the molar ratio of n(Mo):n(Y):n(Al):n(C) = 4:2:3.3:2.7. The positions of C atoms in the crystal of (Mo_2/3Y_1/3)₂AlC were determined. Microstructure and physical and mechanical properties of (Mo_2/3Y_1/3)₂AlC ceramic were systematically investigated. It was found that the obtained (Mo_2/3Y_1/3)₂AlC ceramic had an average grain size of 32.1 ± 3.1 μm in length and 14.2 ± 1.7 μm in width. In terms of physical properties, the measured thermal expansion coefficient (TEC) of (Mo_2/3Y_1/3)₂AlC was 8.99 × 10⁻⁶ K⁻¹, and the thermal capacity and thermal conductivity at room temperature were 0.43 J·g⁻¹·K⁻¹ and 13.75 W·m⁻¹·K⁻¹, respectively. The room temperature electrical conductivity of (Mo_2/3Y_1/3)₂AlC ceramic was measured to be 1.25 × 10⁶ Ω⁻¹·m⁻¹. In terms of mechanical properties, Vickers hardness under 10 N load was measured as 10.54 ± 0.29 GPa, while flexural strength, fracture toughness, and compressive strength were determined as 260.08 ± 14.18 MPa, 4.51 ± 0.70 MPa·m^1/2, and 855 ± 62 MPa, respectively, indicating the promising structural applications.     

Photocatalytic oxidation of ethylene to CO2 and H2O on ultrafine powdered TiO2 photocatalysts: Effect of the presence of O2 and H2O and the addition of Pt

The complete photocatalytic oxidation of C₂H₄ with O₂ into CO₂ and H₂O has been achieved on ultrafine powdered TiO₂ photocatalysts and the addition of H₂O was found to enhance the reaction. The photocatalytic reaction has been studied by IR, ESR, and analysis of the reaction products. UV irradiation of the photocatalysts at 275 K led to the photocatalytic oxidation of C₂H₄ with O₂ into CO₂, CO, and H₂O. The large surface area of the photocatalyst is one of the most important factors in achieving a high efficiency in the photocatalytic oxidation of C₂H₄. The photoformed OH species as well as O ₂ ⁻ and O ₃ ⁻ anion radicals play a significant role as a key active species in the complete photocatalytic oxidation of C₂H₄ with O₂ into CO₂ and H₂O. Interestingly, small amount of Pt addition to the TiO₂ photocatalyst increased the amount of selective formation of CO₂ which was the oxidation product of C₂H₄ and O₂.     

Role of Pt in the Activity and Stability of PtNi/CeO2–Al2O3 Catalysts in Ethanol Steam Reforming for H2 Production

Hydrogen production from ethanol reforming was investigated on bimetallic PtNi catalysts supported on CeO₂/Al₂O₃. Pt content was varied from 0.5 to 2.5 %. Physico-chemical characterization of the as-prepared and H₂-reduced catalysts by TPR, XRD and XPS showed that Pt phase interacted with the Ni and Ce species present at the surface of the catalysts. This interaction leads to an enhancement of the reducibility of both Ni and Ce species. Loadings of Pt higher than 1.0 wt% improved the activity and stability of the Ni/CeO₂–Al₂O₃ catalyst in ethanol steam reforming, in terms of lower formation of coke, C₂ secondary products and a constant production of CO₂ and H₂. The amount and type of carbon deposited on the catalyst was analyzed by TG–TPO while the changes in crystalline phases after reaction were studied by XRD. It was found that for Pt contents higher than 1 wt% in the catalysts, a better contact between Pt and Ce species is achieved. This Pt–Ce interaction facilitates the dispersion of small particles of Pt and thereby improves the reducibility of both Ce and Ni components at low temperatures. In this type of catalysts, the cooperative effect between Pt⁰, Ni⁰ and reduced Ce phases leads to an improvement in the stability of the catalysts: Ni provides activity in C–C bond breakage, Pt particles enhance the hydrogenation of coke precursors (C_xH_y) formed in the reaction, and Ce increases the availability of oxygen at the surface and thereby further enhances the gasification of carbon precursors.     

Yttrium vanadate coupled with cobalt ferrite nanocrystals for enhanced photocatalytic H2 production under visible light irradiation

Yttrium vanadate (YVO₄) nanocrystals are synthesized by a modified sol-gel route followed by coupling with 4.0–16.0 wt% of cobalt ferrite (CoFe₂O₄) nanoparticles. The synthesized heterostructures were laboured for photocatalytic H₂ generation in a water/glycerol system below visible light in the presence of platinum cocatalyst traces. The addition of CoFe₂O₄ nanoparticles has improved the physicochemical characteristics of YVO₄ in terms of light harvesting and photoinduced charge separation. The 12.0 wt% CoFe₂O₄/YVO₄ indicates the narrowest bandgap of 2.5 eV and the highest visible-light activity with a slight reduction of its surface area from 185 to 168 m² g⁻¹. Moreover, the H₂ evolution rate has augmented utilizing this photocatalyst at 2.557 mmol g⁻¹h⁻¹ compared to 0.044 mmol g⁻¹h⁻¹ over the pure YVO₄. Furthermore, the dose optimization of 12% CoFe₂O₄/YVO₄ at 2.0 gL⁻¹ has endorsed the photocatalytic generation of H₂ to 3.389 mmol g⁻¹h⁻¹ with recyclability of 97% after the fifth cycle.     

Aqueous-Phase Reforming of Ethylene Glycol Over Supported Platinum Catalysts

Aqueous-phase reforming of 10 wt% ethylene glycol solutions was studied at temperatures of 483 and 498 K over Pt-black and Pt supported on TiO₂, Al₂O₃, carbon, SiO₂, SiO₂-Al₂O₃, ZrO₂, CeO₂, and ZnO. High activity for the production of H₂ by aqueous-phase reforming was observed over Pt-black and over Pt supported on TiO₂, carbon, and Al₂O₃ (i.e., turnover frequencies near 8-15 min^-1 at 498 K); moderate catalytic activity for the production of hydrogen is demonstrated by Pt supported on SiO₂-Al₂O₃ and ZrO₂ (turnover frequencies near 5 min^-1); and lower catalytic activity is exhibited by Pt supported on CeO₂, ZnO, and SiO₂ (H₂ turnover frequencies lower than about 2 min^-1). Pt supported on Al₂O₃, and to a lesser extent ZrO₂, exhibits high selectivity for production of H₂ and CO₂ from aqueous-phase reforming of ethylene glycol. In contrast, Pt supported on carbon, TiO₂, SiO₂-Al₂O₃ and Pt-black produce measurable amounts of gaseous alkanes and liquid-phase compounds that would lead to alkanes at higher conversions (e.g., ethanol, acetic acid, acetaldehyde). The total rate of formation of these byproducts is about 1-3 min^-1 at 498 K. An important bifunctional route for the formation of liquid-phase alkane-precursor compounds over less selective catalysts involves dehydration reactions on the catalyst support (or in the aqueous reforming solution) followed by hydrogenation reactions on Pt.     

Efficient hydrogen production by photocatalytic water-splitting using Pt-doped TiO2 hollow spheres under visible light

Pt doped TiO₂ hollow spheres (Pt/HS-TiO₂) are prepared by a sol–gel method and characterized by XRD, SEM, TEM and UV-visible absorption spectra. In addition, Pt/HS-TiO₂ is employed as the catalyst for photocatalytic hydrogen production from water splitting under visible light irradiation. The results show that Pt/HS-TiO₂ with hollow sphere structure presents excellent photocatalytic hydrogen evolution performance. The hydrogen generation rate can reach more than 1023.71 μmol h⁻¹ g⁻¹ at room temperature and no obvious deactivation is observed after 30 h irradiation. Furthermore, the reactively of Pt/HS-TiO₂ could be reproduced in the repeated cycle. Therefore, Pt/HS-TiO₂ is a promising photocatalyst to efficiently generate hydrogen under visible-light irradiation at room temperature.     

Uniform dispersion of CuO nanoparticles on mesoporous TiO2 networks promotes visible light photocatalysis

Here, we focus our efforts on synthesizing a uniform dispersion of CuO nanoparticles on mesoporous TiO₂ networks for the first time. H₂PtCl₆ was added through a photocatalytic reaction to produce 0.5% Pt/CuO–TiO₂ nanocomposites. XRD patterns confirmed that the prepared TiO₂ formed the anatase phase. TEM images showed close contacts between CuO and TiO₂ with 5–10 nm particle sizes. One of the advantages of the synthesized mesoporous CuO–TiO₂ nanocomposites was the high pore volume (0.540 cm³ g⁻¹) and large surface area (300 m² g⁻¹). The H₂ evolution over the mesoporous 3 wt% CuO–TiO₂ nanocomposites using a glucose hole scavenger [10 vol%] was determined to be ~13000 μmol/g, a value that was 1300 times greater than that of mesoporous TiO₂. The H₂ evolution rate was increased by up to 1300 and 20 times for 3 wt% CuO–TiO₂ and 0.1 wt% CuO–TiO₂ nanocomposites, respectively, compared with that of mesoporous TiO₂. The increase in H₂ evolution over mesoporous CuO–TiO₂ nanocomposites was explained by the increased light harvesting capacity, high glucose molecule diffusion and efficient charge carrier separation. Moreover, the construction of a heterostructure with a p–n CuO–TiO₂ heterojunction expedited the separation of charge carriers and promoted the evolution of H₂. In addition, H₂ evolution was substantially increased by the synergistic effects of Pt and CuO on the mesoporous TiO₂ networks. Photoelectrochemical and photoluminescence measurements were employed to prove the H₂ evolution mechanism over the CuO nanoparticles deposited on the mesoporous TiO₂ networks.     

Preferential CO oxidation over supported Pt catalysts

Preferential CO oxidation reaction has been carried out at a gas hourly space velocity of 46,129 h^?1 over supported Pt catalysts prepared by an incipient wetness impregnation method. Al2O3, MgO-Al₂O₃ (MgO=30 wt% and 70 wt%) and MgO were employed as supports for the target reaction. 1 wt% Pt/Al₂O₃ catalyst exhibited very high performance (X _CO >90% at 175 ^°C for 100 h) in the reformate gases containing CO₂ under severe conditions. This result is mainly due to the highest Pt dispersion, easier reducibility of PtO _x , and easier electron transfer of metallic Pt. In addition, 1 wt% Pt/Al₂O₃ catalyst was also tested in the reformate gases with both CO₂ and H₂O to evaluate under realistic condition.     

Supercritical CO2-assisted extrusion foaming: A suitable process to produce very lightweight acrylic polymer micro foams

A strategy of CO₂-assisted extrusion foaming of PMMA-based materials was established to minimize both foam density and porosities dimension. First a highly CO₂-philic block copolymer (MAM: PMMA-PBA-PMMA) was added in PMMA in order to improve CO₂ saturation before foaming. Then the extruding conditions were optimized to maximize CO₂ uptake and prevent coalescence. The extruding temperature reduction led to an increase of pressure in the barrel, favorable to cell size reduction. With the combination of material formulation and extruding strategy, very lightweight homogeneous foams with small porosities have been produced. Lightest PMMA micro foams (ρ = 0.06 g cm⁻³) are demonstrated with 7 wt% CO₂ at 130°C and lightest blend micro foams (ρ = 0.04 g cm⁻³) are obtained at lower temperature (110°C, 7.7 wt% CO₂). If MAM allows a reduction of T^foaming, it also allows a much better cell homogeneity, an increase in cell density (e.g., from 3.6 10⁷ cells cm⁻³ to 2 to 6 10⁸ cells cm⁻³) and an overall decrease in cell size (from 100 to 40 μm). These acrylic foams produced through scCO₂-assisted extrusion has a much lower density than those ever produced in batch (ρ ≥ 0.2 g cm⁻³).     

Oxygen-vacancy-assisted construction of Ce–TiO2 aerogel for efficiently boosting photocatalytic CO2 reduction without any sacrifice agent

The development of efficient photocatalysts with high activity and high selectivity remains the biggest challenge limiting the development of photocatalysis. Herein, a novel Ce-doped TiO₂ aerogel (Ce–TiO₂) is synthesized via a simple one-step sol-gel technique, which integrates simultaneously supercritical drying, heat treatment, nano structuring, and self-diffusion for the formation of the Ce embedded in porous TiO₂ matrix with strong coupling. The Ce–TiO₂ aerogel exhibits typically homogeneous structures, and the resulting Ce–TiO₂ aerogel shows an extremely large BET specific surface area of 246.53 m²/g, which is responsible for the much-enhanced photocatalytic active sites. The incorporation of Ce has induced an impurity level in the band gap of the pristine TiO₂ aerogel, extending the light response range to the visible region. Meanwhile, the structural and compositional advantages are exploited to achieve fast separation and transfer of charge carriers. The yields of CH₄ and CO are 0.6 and 2.1 μmol/(g·h) under visible light without any additional co-catalysts or sacrificial agents, which are 1.4 and 15.6 times as high as those of pristine TiO₂ aerogel. In addition, the yields of CH₄ and CO are as high as 10.3 and 26.9 μmol/(g·h) under simulated solar spectrum conditions, which are 34.3 and 1.6 times as high as those of pristine TiO₂ aerogel. The density function theory (DFT) calculation confirms that the resulting Ce–TiO₂ aerogel enables efficient H₂O and CO₂ adsorption and activation through the Ce cooperation and O vacancy, which greatly improves photocatalytic CO₂ reduction. This work reveals the development of aerogel photocatalyst for the photoreduction of CO₂ with H₂O and CO₂ as feedstock.