Efficient Photocatalytic CO2 Reduction Research Articles

Well-designed 2D vanadium carbide (V2C) MXenes supported LaCoO3/g-C3N4 heterojunction for highly efficient and stable photocatalytic CO2 reduction to CO and CH4

The fabrication of heterostructure photocatalysts, incorporating co-catalysts to replace noble metals, is a challenging task aimed at enhancing the efficient separation and transfer of photo-induced electrons and holes. Herein, well-designed 2D V2C MXenes cocatalyst-assisted LaCoO3 perovskite-based g-C3N4 composite was investigated for photocatalytic CO2 reduction to cleaner fuels. As a novel cocatalyst, V2C MXene exhibits remarkable potential in forming intimate contact with LaCoO3/g-C3N4 heterojunction, enabling higher visible light absorbance and proficient charge carrier separation. With the optimized LaCoO3/g-C3N4/V2C heterojunction, CH4 and CO yield rates of 332 and 171 µmol g−1 h−1 were obtained with their selectivity of 34% and 66%, respectively. This substantially higher photocatalytic activity for CO2 reduction with CH4 as the main product was 11.85, 11.10, and 6.91 times greater than LaCoO3, g-C3N4, and LaCoO3/g-C3N4, respectively. The performance of the composite was further investigated under various operating parameters such as the effect of sacrificial reagent, catalyst loading and pressure. The highest CO and CH4 generation rates were achieved with a pressure of 0.4 bars, which was due to the increased rate of CO2 attachment over the V2C-assisted nanotexture. Among the water, methanol and hydrogen sacrificial reagents, the highest photoactivity was achieved with H2, 1.33 folds more than using water for CH4 production, due to involving CO2 methanation reaction with efficient charge carrier generation. Thus, V2C MXene can be used as a promising cocatalyst to replace noble metals and would be used for photocatalytic CO2 reduction to solar fuels and can also be used for other solar energy applications.

Unraveling the Transformation from Type-II to Z-Scheme in Perovskite-Based Heterostructures for Enhanced Photocatalytic CO2 Reduction.

The ability to create perovskite-based heterostructures with desirable charge transfer characteristics represents an important endeavor to render a set of perovskite materials and devices with tunable optoelectronic properties. However, due to similar material selection and band alignment in type-II and Z-scheme heterostructures, it remains challenging to obtain perovskite-based heterostructures with a favorable electron transfer pathway for photocatalysis. Herein, we report a robust tailoring of effective charge transfer pathway in perovskite-based heterostructures via a type-II to Z-scheme transformation for highly efficient and selective photocatalytic CO2 reduction. Specifically, CsPbBr3/TiO2 and CsPbBr3/Au/TiO2 heterostructures are synthesized and then investigated by ultrafast spectroscopy. Moreover, taking CsPbBr3/TiO2 and CsPbBr3/Au/TiO2 as examples, operando experiments and theoretical calculations confirm that the type-II heterostructure could be readily transformed into a Z-scheme heterostructure through establishing a low-resistance Ohmic contact, which indicates that a fast electron transfer pathway is crucial in Z-scheme construction, as further demonstrated by CsPbBr3/Ag/TiO2 and CsPbBr3/MoS2 heterostructures. In contrast to pristine CsPbBr3 and CsPbBr3/TiO2, the CsPbBr3/Au/TiO2 heterostructure exhibits 5.4- and 3.0-fold enhancement of electron consumption rate in photocatalytic CO2 reduction. DFT calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy unveil that the superior CO selectivity is attributed to the lower energy of *CO desorption than that of hydrogenation to *HCO. This meticulous design sheds light on the modification of perovskite-based multifunctional materials and enlightens conscious optimization of semiconductor-based heterostructures with desirable charge transfer for catalysis and optoelectronic applications.

Coaxial electrospinning prepared Cu species loaded SrTiO3 for efficient photocatalytic reduction of CO2 to CH3OH

Photocatalytic CO2 reduction plays an important role in solving environmental issues and alleviating the energy crisis. However, it is still challenging to distribute the surface-active site on photocatalysts with efficient separation of carriers in rational. Herein, the Cu species loaded SrTiO3 nanofiber was constructed through coaxial electrospinning which could realize the dispersion of the Cu site on the one-dimensional (1D) nanofiber structure. The 1D nanofiber with Cu site exhibited superior performance on photocatalytic CO2 reduction based on the excellent ability of charge separation. The Cu2O and CuO were determined to be located on the surface of 1D SrTiO3 nanofiber by the TEM and XPS. The work functions of SrTiO3, Cu2O, and CuO were calculated to be 5.26, 5.47, and 5.51 eV, respectively, suggesting that the carriers could transfer from SrTiO3 nanofiber to the Cu species. The yield of CH3OH with the optimized 8%Cu-SrTiO3 catalyst could reach 8.08 ± 0.03 µmol⋅g−1⋅h−1. This work provided a coaxial electrospinning strategy to load the Cu species active site on the surface of 1D SrTiO3 nanofiber for enhancing photoreduction CO2.

Facilely tunable dodecahedral polyoxometalate framework loaded with mono- or bimetallic sites for efficient photocatalytic CO2 reduction

Utilizing solar energy to drive the conversion of CO2 into high-value chemicals emerged as a promising approach to decrease CO2 emission. Yolk-shell or hollow structure have drawn much attention for photocatalytic CO2 reduction, owing to their efficient CO2 trapping and more active sites exposing. In this study, we employed a simple method to regulate the morphological evolution of K3PW12O40 dodecahedra. After annealing, mono-/bimetallic active species are homogeneously dispersed on K3PW12O40 framework forming PW12 @Co and PW12 @CoNi, which exhibit good CO production rates of 11.2 and 15.1 μmol/h, respectively, with selectivity of 90.7% and 92.6%. The differences in the activity and selectivity of CO2RR are attributed to the morphology variations of POM and the influence of mono-/bimetallic species. These results are confirmed through the analysis of SEM, TEM, N2 and CO2 adsorption/desorption, PL, EIS and SPV characterizations. In-situ DRIFTS and DFT provide further support for the formation and transformation of intermediate products.

Preparation of highly dispersed Ni single-atom doped ultrathin g-C3N4 nanosheets by metal vapor exfoliation for efficient photocatalytic CO2 reduction

Single-atom photocatalysts can modulate the utilization of photons and facilitate the migration of photogenerated carriers. However, the preparation of single-atom uniformly doped photocatalysts is still a challenging topic. Herein, we propose the preparation of Ni single-atom doped g-C3N4 photocatalysts by metal vapor exfoliation. The Ni vapor produced by calcining nickel foam at high temperature accumulates in between g-C3N4 layers and poses a certain vapor pressure to destroy the interlayer van der Waals forces of g-C3N4. Individual metal atoms are doped into the structure while exfoliating g-C3N4 into nanosheets by metal vapor. Upon optimization of Ni content, the Ni single atom doped g-C3N4 nanosheets with 2.81 wt% Ni exhibits the highest CO2 reduction performance in the absence of sacrificial agents. The generation rates of CO and CH4 are 19.85 and 1.73 μmol g−1h−1, respectively. The improved photocatalytic performance is attributed to the anchoring Ni of single atoms on g-C3N4 nanosheets, which increases both carrier separation efficiency and reaction sites. This work provides insight into the design of photocatalysts with highly dispersed single-atom.

Reasonable design pentamerous artificial photosynthesis system for efficient overall CO2 reduction

Inspired by the photosynthesis of green plants in nature, an artificial photosynthesis system of MF/Co-BWO/CPB-Cu with “root”, “trunk” and “leaf” is designed in this study, realizing efficient overall photocatalytic CO2 reduction reaction (CO2RR). Melamine foam (MF) with strong hydrophilicity and abundant porosity is selected as “root” and “trunk”, which can store and transfer liquid H2O. For the “leaf” design, Bi2WO6 and CsPbBr3 are selected as oxidation and reduction photocatalysts, respectively, which would generate Bi2WO6/CsPbBr3 S-scheme heterojunction. CuS and CoO as reduction and oxidation centers are also introduced into photosynthesis system, respectively. CuS plays an important role in CO2 adsorption and activation, while CoO could promote H2O oxidation and supply proton. Moreover, Co-BWO/CPB-Cu as “leaf” could trigger the “transpiration” from MF via photo-thermal effect, inducing the formation of gas–solid biphase CO2RR system. As a result, the artificial photosynthesis system of MF/Co-BWO/CPB-Cu exhibits the efficient CO2RR efficiency.

Proton Turnover Dominated Cascade Route for CO2 Photoreduction

AbstractPhotoreduction carbon dioxide (CO2) and water (H2O) into valuable chemicals is a huge potential to mitigate immoderate CO2 emissions and energy crisis. To date, tremendous attention is concentrated on the improvement of independent CO2 reduction or H2O oxidation behaviors. However, the simultaneous control of efficient electron and hole utilization is still a huge challenge due to the complex cascade redox reactions. Here, a proton turnover exists in the whole CO2 photoreduction process is discovered, which is defined as the pivot to concatenate the hole and electron behaviors. As a demonstration of the concept, the efficient activated hydrogen (*H) production centers of copper (Cu) and rapid hydrogenation centers of nickel (Ni) are coupled by an alloying strategy, and the proton turnover behaviors could be directly determined by adjustment of the molar ratios of CuxNiy. Moreover, Cu3Ni1–TiO2 exhibits the highest electron selectivity of 93.7% for methane (CH4) production with a rate of 175.9 µmol g−1 h−1, while Cu1Ni5–TiO2 reaches up to the highest carbon monoxide (CO) electron selectivity and generation rate at 84.4% and 164.6 µmol g−1 h−1, respectively. Consequently, the experimental and theoretical analysis all clarify the predominate proton turnover effect during the overall CO2 photoreduction process, which directly determines the categories and generated efficiency of C‐based products by regulating variable reaction pathways. Therefore, the revelation of the proton turnover pivot could broaden the new sights by bidirectional optimization of dynamics during the overall CO2 photoreduction system, which favors the efficient, selective, and stable photocatalytic CO2 reduction with H2O.

Efficient photocatalytic CO2 reduction coupled with selective styrene oxidation over a modified g-C3N4/BiOBr composite with high atom economy

A modified g-C3N4/BiOBr composite is developed for photocatalytic CO2 reduction to CO coupled with selective styrene oxidation.

Carbon nitride nanosheet-supported CuO for efficient photocatalytic CO2 reduction with 100% CO selectivity.

The optimal ratio of reaction solutions resulted in excellent performance and product selectivity of CuO/g-C3N4 composites in the photocatalytic CO2 reduction reaction. A pH-dependent chemical exchange saturation transfer (CEST) imaging nuclear magnetic resonance (NMR) method was used to confirm that CuO modification improves the adsorption capacity of CO2.

Synthesis of small size lead-free Cs3Bi2xSb2−2xBr9 solid-solutions using a spatially confined growth method for efficient photocatalytic CO2 reduction

The small size lead-free Cs3Bi0.6Sb1.4Br9 solid-solution spatially confined in MCM-41 molecular sieve shows an outstanding performance for photocatalytic CO2 reduction to CO.

Construction of 2D BiOIO3/ rod-shaped Zn-MOF II-scheme heterojunction for enhanced photocatalytic CO2 reduction to CO without sacrificial reagents

The conversion of CO2 into useable energy materials through photocatalytic reactions has attracted much attention. In this paper, 2D BiOIO3/rod-shaped Zn-MOF type II heterojunction was constructed for efficient photocatalytic CO2 reduction. XRD, SEM, TEM, XPS, and photoelectrochemical characterization tests were used to investigate the physicochemical properties of the prepared photocatalysts. Under 300 W Xenon lamp without any sacrificial reagents, the composite material BiOIO3/Zn-MOF-15(BOIOZ-15) showed the best photocatalytic efficiency, with a CO generation rate of 58.82 μmol/g/h, which is 1.7 times that of BiOIO3. The formation of a type II heterojunction between BiOIO3 and Zn-MOF-15 reduced the photogenerated electron-hole pair compounding, enhanced the separation and transport of photogenerated carriers, and improved the photocatalytic reaction performance of the composites.

Ligand Defect-Induced Active Sites in Ni-MOF-74 for Efficient Photocatalytic CO2 Reduction to CO.

The conversion of CO2 into valuable carbon-based products using clean and renewable solar energy has been a significant challenge in photocatalysis. It is of paramount importance to develop efficient photocatalysts for the catalytic conversion of CO2 using visible light. In this study, the Ni-MOF-74 material is successfully modified to achieve a highly porous structure (Ni-74-Am) through temperature and solvent modulation. Compared to the original Ni-MOF-74, Ni-74-Am contains more unsaturated Ni active sites resulting from defects, thereby enhancing the performance of CO2 photocatalytic conversion. Remarkably, Ni-74-Am exhibits outstanding photocatalytic performance, with a CO generation rate of 1380 µmol g-1 h-1 and 94% CO selectivity under visible light, significantly surpassing the majority of MOF-based photocatalysts reported to date. Furthermore, experimental characterizations reveal that Ni-74-Am has significantly higher efficiency of photogenerated electron-hole separation and faster carrier migration rate for photocatalytic CO2 reduction. This work enriches the design and application of defective MOFs and provides new insights into the design of MOF-based photocatalysts for renewable energy and environmental sustainability. The findings of this study hold significant promise for developing efficient photocatalysts for CO2 reduction under visible-light conditions.

Cayanamide Group Functionalized Crystalline Carbon Nitride Aerogel for Efficient CO2 Photoreduction

AbstractFor photocatalytic CO2 reduction, traditional amorphous polymeric carbon nitride (PCN) has suffered from fast photoexcited electron‐hole recombination and low specific surface area, resulting in low photocatalytic activity. Herein, starting from thermally polymerized PCN, cayanamide groups (─CN) functionalized crystalline carbon nitride (CCN) self‐supporting aerogels are obtained through a molten‐salt and self‐assembly two‐step strategy, which realized efficient photocatalytic CO2 reduction into CO as the main reduction products and O2 as the oxidation product, with CO evolution rate and selectivity reaching 25.7 µmol g−1 h−1 and 93.8%, respectively. It is revealed that the self‐supporting porous aerogel structure can enhance the mass transport of reactants and products, and increase the light absorption ability via multiple photon reflection. With charge carrier separation greatly enhanced in CCN aerogels with high crystallinity as revealed by charge carrier dynamics investigations, theoretical calculations and in situ spectral characterizations evidence that the introduced ─CN groups would act as the active sites for photoreduction of CO2 into CO, with energy barrier greatly reduced for the formation of COOH* intermediates, the rate‐determining step for CO2─to─CO reduction. This work demonstrates a novel and controllable strategy to develop semiconducting polymers with crystal, molecular and morphological structures synergistically modulated for highly efficient and selective photocatalytic CO2 reduction.

(Invited) Dye-Sensitized Molecular Photoelectrodes for CO2 Reduction Using Water as a Reductant

Photocatalytic CO2 reduction using visible light and water as a reductant has been one of the important targets for solving global warming problem and shortage of energy and carbon resources. In this presentation, I talk about two projects, i.e., (1) supramolecular photocatalysts with both functions as photosensitizer and catalysts and (2) photocatalytic CO2 reduction coupled to water oxidation.(1) Highly efficient supramolecular photocatalysts for CO2 reduction1-3 Since CO2 is the most oxidized state of carbon, one-electron reduction of CO2 is an extraordinarily high endergonic reaction. From the viewpoints of low-energy light application, the multi-electron reduction of CO2 via chemical reactions promises to be a more valuable process. This is a main reason why both a photosensitizer and a catalyst are required to promote efficient photocatalytic CO2 reduction. We have developed so-called supramolecular photocatalyts that have both the photosensitizer and the catalyst units. This bonding in the supramolecular photocatalysts can accelerate electron transfer between the two units, which improves the performance of the photocatalytic system, especially on the surface of photofunctional solid materials as described below.(2) Molecular photoelectrodes for photocatalytic CO2 reduction with water as a reductant 1,4 The molecular photocatalytic systems have a weakness, i.e., weak oxidation power in the excited state. For practical application, water should be used as an electron donor. For overcoming this problem, we have developed a hybrid system consisting of the supramolecular photocatalyst and semiconductor electrodes. The hybrid photoelectrochemical cell consisting of this hybrid photocathode and n-type semiconductor photoanode induced visible-light-driven CO2 reduction with water as a reductant to generate CO and O2. References “Photocatalytic Systems for CO2 Reduction: Metal-Complex Photocatalysts and Their Hybrids with Photofunctional Solid Materials” Kumagai, H.; Tamaki, Y.; Ishitani, O., Acc. Chem. Res. 2022, 55, 978-990.“Mechanistic study of photocatalytic CO2 reduction using a Ru(II)-Re(I) supramolecular photocatalyst” Kamogawa, K.; Shimoda, Y.; Miyata, K.; Onda, K.; Yamazaki, Y.; Tamaki, Y.; Ishitani, O., Chem. Sci. 2021, 12, 9682-9693.“Supramolecular Photocatalysts for the Reduction of CO2” Tamaki, Y.; Ishitani, O., ACS Cat. 2017, 7, 3394-3409.“Supramolecular photocatalysts fixed on the inside of the polypyrrole layer in dye sensitized molecular photocathodes: application to photocatalytic CO2 reduction coupled with water oxidation. Kuttassery, F.; Kumagai, H.; Kamata, R.; Ebato, Y.; Higashi, M.; Suzuki, H.; Abe, R.; Ishitani, O., Chem. Sci. 2021, 12, 13216-13232. Figure 1

Top-down synthesis of high-performance lead-free double layer perovskite Cs4CuSb2Cl12 with large specific surface area and rich defects for efficient photocatalytic CO2 reduction

In recent years, there has been significant progress in the field of perovskite research. One area that has garnered attention is lead-free perovskite due to its stability, lack of toxicity, and exceptional optical properties. In this study, we successfully synthesized environmentally friendly, small-sized double-layer perovskites Cs4CuSb2Cl12 using a top-down method involving ball milling. The resulting Cs4CuSb2Cl12 nanoparticles exhibit high photocatalytic capacity, with a 1.60-fold increase in CO yield under full spectrum irradiation for 4 h, from 45.01 μmol/g to 72.17 μmol/g compared to the original material. Additionally, CO evolution under NIR light illumination for 4 h increased from 2.31 μmol/g to 5.37 μmol/g. The top-down treatment resulted in smaller particle size and larger specific surface area, shortened carrier transmission distance, and enhanced electron concentration. Furthermore, the material’s surface presented a high concentration of defects, displayed high absorption capability across the entire spectrum, and abundant photocatalytic active sites. This study introduces an effective and environmentally-friendly strategy to enhance the photocatalytic efficiency of Cs4CuSb2Cl12, providing a new perspective for providing the photocatalytic capability of these materials.

Novel oxygen vacancy-enriched Bi2MoO6-x/MoS2 S-scheme heterojunction for strengthening photocatalytic reduction CO2 and efficient degradation of levofloxacin hydrochloride: Mechanism, DFT calculations

Constructing new photocatalysts for the photocatalytic reduction of CO2 and efficient degradation of Levofloxacin is of great importance to renewable energy. Here, S-scheme Bi2MoO6-x/MoS2 heterojunction nanospheres containing abundant surface defects (oxygen vacancies) were designed and successfully synthesized to enhance CO2 photoreduction activity in the absence of other sacrificial agents, co-catalysts or photosensitisers. At the same time, it can efficiently degrade organic pollutants (Levofloxacin). This heterogeneous structure with surface defects provides an abundance of reactive sites, accelerates charge separation and improves oxidation capacity. The improved Bi2MoO6-x/MoS2 heterogeneous nanospheres show excellent performance under simulated solar light, with the selectivity and yield of 92.45% and 29.01 µmol h−1, respectively, for the generation of CO. Under visible light, the degradation efficiency of levofloxacin hydrochloride (LVX) reached 96.3% within 25 min and remained as high as 95% after three cycles. This work provides a new idea for the design of new S-scheme photocatalysts and an important reference for the preparation of photocatalysts for the efficient photocatalytic reduction of CO2 and the efficient degradation of organic pollutants at the same time.

Facile Synthesis of Ni3+/Co3+ Ion-Doped Zn2SnO4 Microspheres toward Efficient Photocatalytic CO2 Reduction

The photocatalytic reduction of CO2 into hydrocarbons is a promising solution for the energy crisis and greenhouse gas emissions. Thus, the fabrication and development of a new type of photocatalyst is of great importance for the practical application of CO2 reduction. Herein, we report a facile synthesis of Zn2SnO4 (ZTO) microspheres doped with Co3+ ions or Ni3+ ions. The doped Co3+/Ni3+ ions substitute the lattice Zn/Sn ions. DFT calculations and experimental results reveal that the doped Co3+/Ni3+ ions would induce new doping energy levels in the band gap, extend the light response from the UV to the visible region, and separate the charge carriers. As a result, compared with pure ZTO, the photocatalytic activity of a CO2 reduction into CH4 is significantly improved for Co-doped ZTO (Co-ZTO) and Ni-doped ZTO (Ni-ZTO).

Water-activation-facilitated photocatalytic CO2 reduction by a heterogeneous synergetic single-atomic Zn sites and Pd nanocrystals

Enhancing the photoreduction of carbon dioxide (CO2) to produce valuable chemicals, such as carbon monoxide (CO), is of significant importance. The bottleneck in developing advanced catalysts lies in the rational design of catalytic centers with efficient CO2 activation and hydrogen proton production. In this work, palladium nanoparticles (Pd NPs) were successfully modified on UiO-66-NH2-Zn SAs (UN-Zn SAs) by a photo-deposition method. The optimized photocatalyst, 4 Pd NPs-UN-0.7Zn SAs, demonstrated exceptional performance in converting CO2 to CO, exhibiting approximately 1.4-fold and 7.8-fold enhancements compared to UN-0.7Zn SAs and UN, respectively. A combination of time-resolved photoluminescence spectroscopy and electron paramagnetic resonance results unveiled that the introduction of Pd NPs effectively promoted the photogenerated charge separation and facilitated water activation to produce more hydrogen protons. The generated hydrogen protons were subsequently coupled with nearby CO2 that was activated by Zn SAs, thus achieving the facile water-activation-induced CO2 reduction process. Theoretical calculations further confirmed that the heterogeneous synergistic effects between Zn SAs and Pd NPs lowered the energy barrier for the rate-limiting step of CO2 conversion to COOH* , thereby achieving efficient photocatalytic CO2 reduction reactions. This work provides a new perspective on the development of efficient catalysts for the effective conversion of CO2.

Multicomponent Self-assembly of a Multinuclear Heterometal–Organic Polymer for CO2 Reduction

To address the greenhouse effect, scientists have never stopped exploring efficient photocatalytic CO2 reduction systems, and metal-organic compounds have recently emerged as a solution for overcoming global warming and climate issues. Under the irradiation of visible light, the catalytic activity, stability, and selectivity of most of the non-noble metal complexes reported so far are unsatisfactory. To efficiently fix CO2, Ru multinuclear heterometal–organic compound was obtained for carbon dioxide reduction. The as-synthesized M-Zn complex (M =Ru) catalysts exhibit special catalytic activity for the reduction of CO2 because of the immobilized metal ions serving as active sites during the reaction. This study proposes a general strategy for CO2 reduction through high levels in metal-organic polymers to achieve effective environmental protection and governance.

Facile fabrication of binary g-C3N4/NH2-MIL-125(Ti) MOF nanocomposite with Z-scheme heterojunction for efficient photocatalytic H2 production and CO2 reduction under visible light

A binary g-C3N4/NH2-MIL-125(Ti) MOF nanocomposite was fabricated through a facile sonochemical-assisted thermal approach for enhanced photocatalytic H2 production and CO2 reduction under visible light. Compared to pure g-C3N4, the g-C3N4/MOF photocatalyst showed enhanced visible light absorption with promoted charge carrier separation which increased the H2 production rate and the CO2 reduction into CH4 and CO. This enhancement was attributed to the successfully constructed Z-scheme heterojunction in addition to the visible-active, large surface area and highly CO2 adsorbable NH2-MIL-125(Ti) MOF. The highest H2 production of 480 µmol g−1 was exhibited over the g-C3N4/NH2-MIL-125(Ti) nanocomposite with 20 wt% MOF. Similarly, the highest CO production rate of 338 µmol g−1 was achieved with 20 wt% MOF composite. However, for the CH4 product gas, it was observed that the highest production rate was attained with pure g-C3N4 which reveals the NH2-MIL-125(Ti) MOF selectivity towards CO production instead of CH4. Among all the investigated sacrificial agents for H2 production, methanol was the best. The performance of CO2 reduction process was found to be increasing with the pressure increase. Furthermore, the stability investigations revealed continuous productions of H2, CO and CH4 over the C3N4/MOF photocatalyst in multiple cyclic runswithout any significant photocatalyst deactivation. This study provides new ideas for the fabrication of cheap, efficient and easy-synthesized nanomaterials for energy production and environmental remediation applications.