Photocatalytic CO2 Reduction Research Articles

Interface engineering on single-atom Cu-modified BiOBr1−xClx for efficient artificial photosynthesis of methanol

Converting CO2 into value-added fuels was an attractive way to alleviate the energy crisis. Cu-based catalysts were recognized as the most effective candidates for catalyzing CO2 to solar fuels due to their specific electronic structure. However, selective production of desired fuels from photocatalytic CO2 reduction remained a grand challenge. Herein, the interface engineering of single-atom Cu with BiOBr1−xClx nanosheets (Cu-SA/BOBC) was demonstrated to address this challenge. The single-atom Cu in BOBC favored charge transition, carrier separation, and photon utilization, with a superior performance of CO2 photoreduction yielding CH3OH of 8.21 μmol·g−1·h−1, 94.3 % electron-based CH3OH selectivity. Meanwhile, it could lower the CO2 activation energy barrier, and be conducive to strong CO* adsorption and subsequent hydrogenation of CO* to CHO*, which was critical for the high selectivity of CH3OH. This work highlighted a new insight into regulating the photoreduction of CO2 to CH3OH by interfacial interaction.

Crystal plane engineering-tailored Co-Ni bimetallic sites in CoNiO2 to achieve efficient photocatalytic CO2 reduction

Aligning the atomic structure of catalyst by the crystal-plane engineering is an effective strategy to enhance the photocatalytic activity. In this paper, the CoNiO2 nanosheets (NSs) with (200) and nanorods (NRs) with (111) crystal planes were successfully prepared through a simple hydrothermal method for CO2 photoreduction. The experimental results indicated that the CNO NRs had excellent CO2 photoreduction performance. The CO and CH4 yields over CNO NRs were about 48.66 and 5.84 μmol·g-1·h-1, which were about 2.62 and 2.61 times stronger than that of CNO NSs. Moreover, it was also about 10.70 and 6.25 times as good as the TiO2 commercial powder, respectively. Experimental and theoretical calculations demonstrated that the Co-Ni bimetallic sites on the (111) crystal plane of CNO NRs can effectively enhance the CO2 adsorption and activation ability compared with the single Ni site on the (200) crystal plane of CNO NSs. Besides, the energy barrier required for the development of the critical intermediate *COOH from *CO2 was greatly reduced on the Co-Ni bimetallic sites, thereby improving the CO2 photoreduction activity. The reaction paths were inferred by in-situ FTIR and 13C isotope tracer techniques, and finally a potential enhancement mechanism of the crystal plane engineering induces bimetallic sites to promote CO2 adsorption and activation process has been proposed.

Regulated charge transfer by cascade dual Z-scheme heterojunction of HCdS@ZnIn2S4-Cobalt porphyrin for efficient photocatalytic solar fuel production

Dual Z-schemed photocatalysts possess superior charge-separation efficiency and powerful redox capabilities, which have attracted significant attention in photocatalytic CO2 reduction (PCR). However, most of the dual Z-scheme systems are focused on inorganic semiconductors, which remain a challenge to control the selectivity of PCR products. Herein, we designed a cascade dual Z-scheme structured organic/inorganic heterojunction of HCdS@ZnIn2S4-Cobalt porphyrin (HCdS@ZIS-CoTPPS). HCdS@ZIS-CoTPPS demonstrated excellent PCR activity (CO rate: 93.64 μmol·g−1·h−1) and adjustable syngas ratio when compared to HCdS, ZIS, CoTPPS, and HCdS/ZIS. Experimental characterizations and density functional theory (DFT) calculations reveal that the superior PCR activity of HCdS@ZIS-CoTPPS is contributed by the broad light absorption range, short charge carrier migration path, low interface contact resistance, and strong redox ability induced by the hollow structured cascade dual Z-scheme heterojunction. This article provides valuable inspiration for the design and preparation of atomistic heterojunctions for solar-driven fuel generation.

Z-scheme ZnIn2S4/CuxO heterostructure on flexible substrate for efficient photothermal catalytic CO2 reduction

The ZnIn2S4 nanosheets were successfully synthesized on the surface of compacted stainless steel mesh using a simple solvothermal method, and further modified with CuxO nanoparticles to form ZnIn2S4/CuxO heterojunction photocatalyst via a wet chemistry approach. These photocatalysts were then utilized for photothermal catalytic CO2 reduction under full spectrum solar light. The experimental results demonstrated that the deposition of the photocatalyst on the flexible substrate effectively prevented the aggregation of ZnIn2S4 nanosheets. The incorporation of CuxO nanoparticles enhanced the specific surface area of the photocatalyst, and created a Z-scheme heterojunction with ZnIn2S4 to improve the utilization efficiency of photogenerated electrons. It was noteworthy that the dark red CuxO exhibited a full spectrum response and excellent photothermal effect, thereby facilitating carrier migration and reducing CO2 catalytic reaction barriers. Consequently, the optimized ZnIn2S4/CuxO exhibited significantly enhanced CO2 to CO yield of 1515.8 μmol m-2h−1 and CH4 yield of 1579.4 μmol m-2h−1, which was about 7.5 and 7.6 times higher than those achieved by pure ZnIn2S4, respectively. Furthermore, this study provided detailed insights into the mechanism of photocatalytic CO2 reduction over composite material as well as valuable guidance for designing immobilized photocatalysts with high activity for CO2 reduction.

Efficient photocatalytic CO2 and Cr(VI) reduction on carbon spheres/g-C3N4 composites with enriched nitrogen vacancies

In this study, carbon spheres (CS)/g-C3N4 composite materials were fabricated by a hydrothermal method, and the characterizations have confirmed the successful anchoring of CS onto the surface of g-C3N4, constructing enriched nitrogen vacancies during the synthesis process. The photocatalytic CO2 reduction activity of g-C3N4 is enhanced by all of these advantageous factors. The significant enhancement can be attributed to the tight interfacial interaction between CS and g-C3N4, which endows with the photocatalyst a larger specific surface area, higher light utilization efficiency and stronger capability for photoinduced charges separation. Furthermore, the presence of nitrogen vacancies further accelerates the separation and migration efficiency of photogenerated charges, provides additional active sites to promote the adsorption and activation of CO2 molecules, thereby effectively boosting the photocatalytic activity for CO2 reduction. The CO2 conversion rate on CS/g-C3N4 composite materials is higher than that on the reference g-C3N4. The apparent quantum yield (AQY) is also superior to that of the reference g-C3N4 under three different monochromatic light irradiations. The stability of the catalyst was verified through cycling experiments, indicating promising potential practical industrial application. The CO2 reduction mechanism and transformation pathways were elucidated using in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The photocatalytic reduction rate constant of Cr(VI) by 50CS/CN is 2.9 times higher than that by CN. This study introduces a facile approach for synthesizing g-C3N4-based photocatalytic materials, providing an interesting strategy to boost photocatalytic activity of g-C3N4 for photocatalytic CO2 and Cr(VI) reduction.

Enhancing photocatalytic performance of rose-shaped Co/Ni bimetallic organic framework for reducing CO2 to CO under visible light

Co-MOF-74, composed of Co salt as the metal source and 2,5-dihydroxyterephthalic acid as the organic ligand, is widely used as a catalyst for the photocatalytic reduction of CO2 due to its open metal sites, high porosity, large specific surface area, and high CO2 adsorption capacity. However, its effectiveness in CO2 conversion is limited by weak electron transfer capabilities and a high rate of electron/hole pair recombination. To address these limitations, a bimetallic strategy was employed to significantly improve the catalytic performance of Co-MOF-74 for photocatalytic CO2 reduction. Stable bimetallic Co/Ni-MOF-74-x (x = 1, 2, 3) with controllable morphology and metal ratios were synthesized by adjusting the molar ratios of Co2+ and Ni2+ and combining them with 2,5-dihydroxyterephthalic acid. The introduction of Ni2+ led to a significant increase in the specific surface area, from 204.999 m2/g (Co/Ni-MOF-74) to 790.873 m2/g (Co/Ni-MOF-74-1). In addition, the band gap of bimetallic Co/Ni-MOF-74-1 was narrowed to 1.4 eV, which enhanced charge transfer. As a result, photocatalytic experiments demonstrated that the CO2 conversion efficiency of bimetallic Co/Ni-MOF-74-1 was significantly improved, reaching 4.539 mmol/g/h, compared to that of the monometallic Co-MOF-74. Finally, a synergistic photocatalytic mechanism involving ligand activation was proposed to explain the reaction process of the bimetallic Co/Ni-MOF-74 catalyst. Meanwhile, this study highlights that the bimetallic strategy is an effective approach to optimizing the performance of MOF catalysts for the photocatalytic reduction of CO2.

Efficient photocatalytic CO2 and Cr(VI) reduction on carbon quantum dots/carbon nitride heterojunctions

Carbon quantum dots (CQDs), known for their exceptional optical properties, hold the potential to enhance light absorption, charges separation and transfer in semiconductor materials. However, using cheap medicinal materials as precursors in the field of photocatalysis to obtain CQDs has seldom concerned. In this study, we utilized biomass-derived CQDs from carbon-rich licorice powder to improve photocatalytic CO2 and Cr(VI) reduction in polymer carbon nitride (PCN). The CQDs/g-C3N4 heterojunctions were synthesized via a hydrothermal method, and the successful fabrication and integration of CQDs on g-C3N4 surfaces were confirmed through detailed characterization. The optimal sample with a licorice powder to PCN mass ratio of 0.05:1 ((50CQDs/CN) demonstrates a tripling in CO2 conversion efficiency under simulated sunlight compared to the reference PCN. Under visible light irradiation, the 50CQDs/CN also performs superior photocatalytic Cr (VI) removal efficiency, which is 2.48 times of that of the reference PCN. This significant boost is attributable to the successful construction of the CQDs/CN heterojunction and the abundance of functional groups on the CQDs surface, which provide more active sites, improve light absorption and increase charges migration rates. The stability of these new photocatalysts was confirmed through repeated photocatalytic cycles, indicating their potential for practical applications. Mechanistic studies reveal insights into the enhanced photocatalytic pathways and intermediate conversion processes. Our findings present a novel, efficient and sustainable route to fabricate g-C3N4-based photocatalysts, offering a promising strategy for further mitigate the greenhouse gas crisis and environmental pollution.

Sulfur-vacancy induced asymmetric active site for Bi19S27Br3 nanorods photocatalyzes CO2 conversion to ethylene

The photocatalytic conversion of CO2 into high value-added C2 products remains a significant challenge due to the limited active sites and high energy barrier of C-C coupling process. Herein, the sulfur-vacancy was established on the surface of Bi19S27Br3 nanorods, leading to the electron on residual S atoms become unstable and active. Under the light irradiation, the photoexcited electron transfer from S atoms to neighboring Bi atoms to generate in-situ charge-polarized Bi(3-x)+ asymmetric active sites, which can enhance CO2 adsorption-activation capacity and regulate C-C coupling process for the C1 intermediate. The experimental results and theoretical calculation confirm that more charges aggregate around the induced Bi atoms, reducing the energy barrier of the C-C coupling reaction and improving C2H4 formation. Consequently, the sulfur-vacancy Bi19S27Br3 nanorods achieve efficient C2H4 generation through photocatalytic CO2 reduction, which C2H4 formation rate is 17.80 µmol g−1 after 5-hour photocatalytic reaction, with the product selectivity and electron selectivity of 49 % and 85 %, respectively, outperforming the low sulfur-vacancy Bi19S27Br3 nanorods by four-folds. This research provides new insights into the design of photocatalysts.

Atmosphere engineering of metal-free Te/C3N4 p-n heterojunction for nearly 100% photocatalytic converting CO2 to CO

Carbon nitride (CN)-based heterojunction photocatalysts hold promise for efficient carbon dioxide (CO2) reduction. However, suboptimal production yields and limited selectivity in CO2 conversion pose significant barriers to achieving efficient CO2 conversion. Here, we present the construction of a p-n heterojunction between ultrasmall Te NPs and CN nanosheet using a novel tandem hydrothermal-calcination synthesis strategy. Through ammonia-assisted calcination, ultrasmall Te NPs are grown in-situ on the CN nanosheets’ surface, resulting in the generation of a robust p-n heterojunction. The synthesized heterojunction exhibits increased specific surface area, reinforced visible light absorption, intensive CO2 adsorption capacity, and efficient charge transfer. The optimum Te/CN-NH3 demonstrates superior photocatalytic CO2 reduction activity and durability, with nearly 100 ​% selectivity for CO and a yield as high as 92.0 ​μmol ​g−1 ​h−1, a fourfold increase compared to pure CN. Experimental and theoretical calculations unravel that the strong built-in electric field of the Te/CN-NH3 p-n heterojunction accelerates the migration of photogenerated electrons from Te NPs to the N site on CN nanosheets, thereby promoting CO2 reduction. This study provides a promising material design approach for the construction of high-performance p-n heterojunction photocatalysts.

Integration of multi-strategy modifications in an Au cocatalyst-loaded 2D/2D BiVO4/P-doped g-C3N4 Z-scheme heterojunction for efficient photocatalytic CO2 reduction

Mimicking nature to fulfill the artificial conversion of CO2 and H2O into solar fuels is an appealing tactic to alleviate energy scarcity and environmental concerns. However, obstacles such as inferior charge separation and light absorption of semiconductors, complex water dissociation, and high CO2 activation energy barrier, immensely restrict photocatalytic CO2 reduction activity. Herein, multi-strategy modifications including element doping, 2D/2D Z-scheme heterojunction construction, and cocatalyst loading, were integrated into an Au-loaded BiVO4/P-doped g-C3N4 composite (Au-BVO/P-CN), which help the photocatalytic system to achieve superior visible light harvest, eminent charge separation, and robust redox capacity. The optimal Au-BVO/P-CN manifests eminent visible light photocatalytic CO2 reduction activity with a CO yield of 20.87 µmol g−1 h−1. The Z-scheme mechanism in Au-BVO/P-CN is verified by the improved photocatalytic CO2 reduction activity and free radical capture experiments. The progressively generated *COOH and *CO intermediatesprobed by in-situ infrared spectroscopy reveal the reason for high CO product selectivity. The synergistic benefits of multi-strategy modifications can inspire future photocatalyst design for efficient solar fuel production.

Restructuring surface frustrated Lewis pairs of MgAl-LDH through isomorphous Co doping for accelerating photocatalytic CO2 reduction

The adsorption of carbon dioxide on the catalyst surface is often neglected, and the improvement of adsorption activation capacity is important to realize the efficient conversion of carbon dioxide. In this paper, a novel layered double hydroxide Co-MgAl-LDH (CML) with frustrated Lewis pairs (FLPs) was successfully prepared by one-step hydrothermal doping of transition metal Co, which Co2+ and the oxygen vacancies brought about by the doping (Co2+-Vo) are the Lewis acid site, and adjacent hydroxyls are the Lewis base site, and In-situ experiments and Density Functional Theory (DFT) demonstrated that the FLPs effectively enhanced the CO2 adsorption activation capacity of CML. The present work provides a new idea for modifying Layered double hydroxides (LDH) to construct FLPs, and also offers new hope for constructing high-performance LDH-based CO2 reduction photocatalysts.

Biphase TiO2\\Zn-tetracarboxy-phthalocyanine twin S-scheme heterojunction nanowires with efficient charge transfer and CO2 photocatalytic conversion

Constructing heterojunction photocatalysts with proper charge transfer channels has been confirmed to be a promising strategy for CO2 photoreduction into chemical fuels. However, promoting photoinduced charge separation in traditional heterojunction catalysts still remains a big obstacle for practical applications. In this work, the TiO2(B)-Anatase\\ZnTcPc twin S-scheme heterojunctions are designed and constructed by loading Zn (II) tetracarboxy phthalocyanine (ZnTcPc) on the prepared TiO2(B)-Anatase biphase TiO2 nanowires by self-assemble strategy. The TiO2(B)-Anatase\\ZnTcPc twin S-scheme heterojunctions effectively promote charge transport across the multi-heterointerfaces and enhance visible light absorption and CO2 adsorption. Thus the optimized hybrid photocatalyst exhibits a remarkable photocatalytic CO2 reduction performance, and the CO yield reaches 237.8μmol g−1h−1. The CO2 photoreduction mechanism and charge transfer properties in the twin S-scheme heterojunction are also investigated and characterized. This research offers a viable approach to enhancing the heterojunction system for excellent photocatalytic performance.

Multi-species defect engineering synergistic localized surface plasmon resonance boosting photocatalytic CO2 reduction

Inadequate charge carrier kinetics and a scarcity of active sites still challenge photocatalytic CO2 reduction reaction (CO2RR). We exploit the synergy between multi-species defect engineering and the localized surface plasmon resonance (LSPR) effect in Bi/BiV1-mO4-m to address these limitations. Theoretical calculations show that V and O defects collectively modulate the work function of BiVO4, which induces hot electrons to transfer from Bi nanoparticles to BiV1-mO4-m. These electrons are then captured by O defects, confirmed by femtosecond transient absorption spectroscopy. Electron density is significantly increased at the O defects, enhancing CO2 adsorption and establishing it as a new reaction site. Bi/BiV1-mO4-m achieves photocatalytic CO2RR in pure water; Bi/BiV1-mO4-m achieves direct solar-driven photocatalytic CO2RR with a CO yield of 501 μmol/g/h under concentrated sunlight.

Constructing functionalized carbon quantum dots on amino-rich graphitic carbon nitride to enhance CO2 photocatalytic reduction: Critical role of functional group modulation

Carbon quantum dots (CQDs) decoration have been widely acknowledged as promising strategy in photocatalysis, yet in-depth understanding of the effect of different functionalized CQDs on CO2 photocatalytic reduction is still lacked. Herein, three kinds of functionalized CQDs, i.e. carboxylic CQDs (CCQDs), amino CQDs (NCQDs) and sulfonated CQDs (SCQDs), were homogeneously anchored on amino-rich g-C3N4 (U1W1-CN) to investigate their CO2 reduction behaviors under simulated solar-light illumination. Structural analysis demonstrated that potential amide covalent bonds formed between U1W1-CN and CCQDs, and noncovalent conjugations might exist between U1W1-CN and SCQDs, while strong electrostatic attraction between U1W1-CN and NCQDs. Performance tests showed CQDs decoration greatly enhanced the CO2 reduction activity, with 7%CCQDs/U1W1-CN exhibiting the optimal CO and CH4 productions of 40.94 μmol g−1 and 2.2 μmol g−1 under 4 h light irradiation, markedly higher than those of 7%SCQDs/U1W1-CN and 7%NCQDs/U1W1-CN. After comprehensive analysis, it was found that CCQDs decoration endowed U1W1-CN with better CO2 adsorption and activation. And due to the potential amide covalent bonds formed between CCQDs and U1W1-CN, 7%CCQDs/U1W1-CN delivered the largest electron density and most abundant COOH– intermediates, contributing much to its superior CO2 reduction activity over 7%NCQDs/U1W1-CN and 7%SCQDs/U1W1-CN. It is expected that the critical role of functional group modulation on CQDs in enhancing CO2 photocatalytic reduction revealed in this work can provide valuable insights into the rational design of more advanced photocatalysts for targeted reactions.

Sulfur-doped Bi2O2CO3 nanosheet for enhanced visible-light-driven photocatalytic CO2 reduction to CO with ultra-high selectivity.

The photocatalytic reduction of carbon dioxide (CO2) has emerged as a compelling strategy for the conversion of renewable energy. However, the expeditious recombination of photogenerated charge carriers and the inadequate light absorption capabilities are currently predominant challenges. Herein, we developed a facile hydrothermal approach to synthesize a sulfur doped Bi2O2CO3 nanosheet with a tunable energy band structure designed to enhance visible light absorption. Our findings indicate that the incorporation of sulfur into the catalytic sites induces an electron sink effect, significantly improving the separation efficiency of photogenerated charge carriers. Consequently, this sulfur-doped Bi2O2CO3 catalyst exhibits a remarkable carbon monoxide (CO) yield of 16.64 μmol gcat-1 h-1 with nearly 100 % selectivity under illumination ranging from 420 to 780 nm. Through in-situ characterization techniques and theoretical calculations, it was revealed that sulfur-coordinated bismuth sites greatly enhance CO2 adsorption and decrease the energy barrier for critical intermediates formation (*COOH), thus selectively driving the reaction towards CO production. This work not only advances our understanding of mechanisms underlying photocatalytic reduction of CO2 on sulfur-doped bismuth-based catalysts but also sets a precedent for developing sophisticated photocatalytic systems for enhanced photoreduction reactions.

Studying the productivity of sewage sludge (SS) components for photocatalytic CO2 transformation to CO and methane

AbstractEnergy-efficient photocatalytic CO2 conversion to sustainable solar fuels is a promising approach for simultaneously resolving energy and environmental concerns. The increased growth of sewage sludge necessitates research and innovation to propose more commercially viable options for lowering the socioeconomic and environmental complications associated with its current treatment. Sewage sludge can be applied to valuable products or used as a feedstock for energy production. According to the characterization results, the sewage sludge contains several metallic oxides (M), including Ni, Al, Mn, and Cu, and semiconductors (Fe2O3 and ZnO). According to the proposed mechanism, ZnO acts as an electron conductor between the Fe2O3 and the active sewage sludge due to forming an n–n type heterojunction. Under visible-light irradiation, photocatalytic CO2 reduction of sewage sludge was investigated using a fixed bed reactor. The CO2 reduction produced CO and CH4, with production rates of 9.76 and 4.20 µmol g−1 h−1, respectively, via the electrical conductivity in the sewage sludge elements. Furthermore, the impacts of photocatalyst loading, system reforming, light effect and pressure range were examined, where the methane yield at 0.1 g was 4.23 and 2.26 times significantly higher than at 0.05 and 0.2 g, correspondingly. With catalyst loadings of 0.1 and 0.2 g, the mono-oxide productivity was 1.69 and 2.58, notably greater, respectively. Moreover, the best yield of the CO and methane was obtained by using 0.3 bar as pressure and 10% methanol in H2O/CO2 as a reducing agent. Finally, using sewage sludge to produce a solar fuel based on the presence of active metallic oxide and semi-conductor heterojunctions provides novel insights from molecular and engineering perspectives into converting CO2 to a green fuel using wastewater sludge. Graphical abstract

Well-designed V2AlC MAX supported g-C3N4/TiO2 Z-scheme heterojunction for photocatalytic CO2 reduction through bi-reforming to produce CO and CH4

Well-designed V2AlC MAX supported g-C3N4/TiO2 Z-scheme heterojunction was synthesized and tested for photocatalytic CO2 reduction through bi-reforming under UV and visible light in batch and continuous photoreactors. Compared to V2AlC/g-C3N4, V2AlC/TiO2 produced 2.17 times more CO and 6.40 times more CH4, along with H2. The highest CO production of 14644 μmol g−1 h−1 was obtained over V2AlC-g-C3N4/TiO2 composite at a selectivity of 20.21 %. Similarly, CH4 and H2 production of 56567 and 1253 μmol g−1 h−1 was obtained, which were 11.11 and 169.9 folds higher for CH4 and 2.77 and 2.32 folds higher for H2 production compared to using g-C3N4/TiO2 and V2AlC/TiO2, respectively. The efficient generation and separation of charge carriers were achieved by the Z-scheme heterojunction of g-C3N4/TiO2 with V2AlC MAX cocatalysts, which led to a greatly increased photocatalytic activity. Using a continuous process, the production of CO was decreased by 1.12 folds, whereas the production of methane disappeared and the reaction pathway was the conversion of CO2 to CO. Using methanol with UV light resulted in higher production of protons and hydrogen, achieving the highest quantum efficiency. The stability study further confirmed the continuous evolution of CO, CH4, and H2 over four cycles.

Metal Center-Tuned Photocatalytic Carbon Dioxide Reduction for Frameworks with the Tetraphenylethene-Imidazole Ligand.

As heterogeneous photocatalysts that can effectively transform CO2 to CO, two MOFs with different metal centers, namely, [M(tipe)(H2O)2](ClO4)2·solvent (M = Ni named as Ni-MOF and M = Co referred to as Co-MOF), were synthesized by reactions of 1,1,2,2-tetrakis(4-(imidazole-1-yl)phenyl)ethene (tipe) with the corresponding metal perchlorate. Both Ni-MOF and Co-MOF have 3D structures, in which the metal centers have the same coordination environment with the N4O2 donor set. Driven by visible light, the CO production catalyzed by Co-MOF is 6734.1 μmol g-1 with 45.3% selectivity, and in contrast, Ni-MOF has 4601.3 μmol g-1 CO production with 97.6% selectivity in 5 h. Through photoelectrochemical characterization, DFT calculations, and in situ FT-IR measurements, the photocatalytic CO2 reduction process catalyzed by Ni-MOF and Co-MOF was investigated. The results show that the metal center of the MOF is crucial for photocatalytic CO2 reduction. This work offers an innovative approach for controlling the performance of photocatalytic CO2 reduction through tuning the metal centers of architectures.

Exchange of CO2 with CO as Reactant Switches Selectivity in Photoreduction on Co–ZrO2 from C1–3 Paraffin to Small Olefins

Photocatalytic reduction of CO2 into C2,3 hydrocarbons completes a C‐neutral cycle. The reaction pathways of photocatalytic generation of C2,3 paraffin and C2H4 from CO2 are mostly unclear. Herein, a Co0–ZrO2 photocatalyst converted CO2 into C1–3 paraffin, while selectively converting CO into C2H4 and C3H6 (6.0 ± 0.6 μmol h−1 gcat−1, 70 mol%) only under UV–visible light. The photocatalytic cycle was conducted under 13CO and H2, with subsequent evacuation and flushing with CO. This iterative process led to an increase in the population of C2H4 and C3H6 increased up to 61–87 mol%, attributed to the accumulation of CH2 species at the interface between Co0 nanoparticles and the ZrO2 surface. CO2 adsorbed onto the O vacancies of the ZrO2 surface, with resulting COH species undergoing hydrogenation on the Co0 surface to yield C1–3 paraffin using either H2 or H2O (g, l) as the reductant. In contrast, CO adsorbed on the Co0 surface, converted to HCOH species, and then split into CH and OH species at the Co and O vacancy sites on ZrO2, respectively. This comprehensive study elucidates intricate photocatalytic pathways governing the transformation of CO2 into paraffin and CO to olefins.

Exchange of CO2 with CO as Reactant Switches Selectivity in Photoreduction on Co-ZrO2 from C1-3 Paraffin to Small Olefins.

Photocatalytic reduction of CO2 into C2,3 hydrocarbons completes a C-neutral cycle. The reaction pathways of photocatalytic generation of C2,3 paraffin and C2H4 from CO2 are mostly unclear. Herein, a Co0-ZrO2 photocatalyst converted CO2 into C1-3 paraffin, while selectively converting CO into C2H4 and C3H6 (6.0±0.6 μmol h-1 gcat -1, 70 mol %) only under UV/Visible light. The photocatalytic cycle was conducted under 13CO and H2, with subsequent evacuation and flushing with CO. This iterative process led to an increase in the population of C2H4 and C3H6 up to 61-87 mol %, attributed to the accumulation of CH2 species at the interface between Co0 nanoparticles and the ZrO2 surface. CO2 adsorbed onto the O vacancies of the ZrO2 surface, with resulting COH species undergoing hydrogenation on the Co0 surface to yield C1-3 paraffin using either H2 or H2O (g, l) as the reductant. In contrast, CO adsorbed on the Co0 surface, converted to HCOH species, and then split into CH and OH species at the Co and O vacancy sites on ZrO2, respectively. This comprehensive study elucidates intricate photocatalytic pathways governing the transformation of CO2 into paraffin and CO to olefins.