CO2 Evolution Rate Research Articles

Adjustment of charge transfer behavior for layered photocatalysts through fabricating face-to-face 2D/2D S-scheme heterojunction toward efficient CO2 reduction

It is a challenging issue to improve charge transfer and separation between neighboring layers of for the layered photocatalysts, because the photogenerated charges are more inclined to migrate within the layer due to their inherent anisotropy. Herein, a new 2D/2D heterojunction is fabricated by implanting Bi2O2S nanoplates into the polymeric carbon nitride (PCN) nanosheets, in which the large area of tightly face-to-face coupling architecture is formed between them that significantly improves the photophysical, photoelectrochemical and electrochemical properties relative to PCN. It is important that this unique architecture induces a strong built-in electric field and gives rise to a S-scheme charge transfer pathway between Bi2O2S and PCN, which effectively conquers the restriction of charge transfer between neighboring layers inside heterojunction, thus significantly improving the whole separation efficiency of photogenerated carriers of the 2D/2D Bi2O2S/PCN heterojunction. As a consequence, the optimal Bi2O2S/PCN-20 heterojunction achieves an average CO evolution rate of 2.61 and 2.15 times that of PCN and Bi2O2S for photocatalytic CO2 reduction reaction, respectively, and exhibits the superior reusability and stability. This work opens a viable design avenue for controlling the charge transfer behavior of anisotropic layered photocatalysts.

In situ construction of S-scheme heterojunctions between BiOCl and Bi-MOF for enhanced photocatalytic CO2 reduction and pollutant degradation

Recently, photocatalytic technology has been widely used as a sustainable method to address environmental pollution issues. Herein, BiOCl/Bi-MOF (BOC/Bi-MOF) based semiconductor photocatalysts with S-scheme heterojunction were fabricated by an in situ growth method, and the photocatalytic activity of the materials was explored for CO2 reduction and pollutant degradation. As confirmed by density functional theory calculations and physiochemical characterizations, the established S-scheme heterojunction confers enhanced carrier separation efficiency and retention of redox capability to the BOC/Bi-MOF. Through an improved combination of charge separation and surface reactions, the prepared BOC/Bi-MOF efficiently reduces CO2 solely to CO. The heterojunction as catalyst is more durable and effective than any of its single component. The CO evolution rate of the optimized composite catalyst was 7.66 and 33.10 times of those of BiOCl and Bi-MOF, respectively. In addition, BOC/Bi-MOF exhibits a high efficiency in the photocatalytic degradation of the pollutant rhodamine B (RhB) in aqueous environments, and the pollutant was completely removed within 20 min. Due to the generation of interfacial potential differences, the internal electric field (IEF) generation at heterogeneous interfaces facilitates the separation and transfer of photogenic charges. This work demonstrated a practical and effective route for in situ growth of S-scheme heterojunctions with high efficiencies in CO2 reduction and RhB degradation.

1D Covalent Organic Frameworks with Tunable Dual-Cobalt Synergistic Sites for Efficient CO2 Photoreduction.

Diatomic catalysts enhance photocatalytic CO2 reduction through synergistic effects. However, precisely regulating the distance between two catalytic centers to achieve synergistic catalysis poses significant challenges. In this study, a series of one-dimensional (1D) covalent organic frameworks (COFs) are designed with adjustable micropores to facilitate efficient CO2 photoreduction. CO2 molecules are anchored between dual-cobalt centers within micropores, thus effectively reducing their activation energy and initiating the photocatalytic process. Additionally, the formation of *COOH intermediates is significantly influenced by the coordination microenvironment around dual-cobalt sites. Notably, COF-Co-N4 exhibited remarkable CO2 photoreduction activity with a CO evolution rate of 110.3 µmol·g-1·h-1, which surpasses most of previously reported single-atom-site photocatalysts. Comprehensive characterization and density functional theory (DFT) calculations revealed that 1D COFs with dual-cobalt sites possess the ability to anchor CO2 molecules, thereby enhancing the efficacy of synergistic catalysis. Simultaneously, COF-Co-N4 with quadruple nitrogen coordination significantly reduced the energy barrier of crucial *COOH intermediate, facilitating efficient photocatalytic CO2 reduction. This study meticulously modulated the coordination microenvironment surrounding dual-cobalt synergistic sites, providing new insight into the design of high-performance photocatalysts.

Zeeman Effect-Boosted Spin-Polarized Band Splitting in Diluted Magnetic Photocatalysis Semiconductors for Efficient CO2 Photoreduction.

Magnetic field regulation is an effective strategy to improve the photocatalytic activity of magnetic semiconductor photocatalysts, but it is not suitable for widely used nonmagnetic photocatalytic semiconductors. Here, we report a Zeeman effect-driven spin-polarized band splitting phenomenon in diluted magnetic semiconductors that show efficient photocatalytic CO2 reduction under visible-light irradiation. A flexible Ni2+-doped BaTiO3 nanofiber film is used as the diluted magnetic semiconductor model to prove this concept. The interstitial Ni2+ dopant induces the spin-polarized bands in Ni-BaTiO3 nanofibers to split under light excitation, generating spin-excited electrons and holes. This Zeeman effect induced by the magnetic field is more obvious since it intensifies the spin-polarized band splitting and generates more spin-excited electrons and holes, suppressing the carrier recombination and extending the carrier lifetime for CO2 photoreduction. As a result, the evolution rates of CO and CH4 are as high as 86.47 and 96.06 μmol/g/h under a small magnetic field of 50 mT. The proposed mechanism of Zeeman effect-driven spin-polarized band splitting is feasible to improve the CO2 photoreduction efficiency of broadly applied diluted magnetic semiconductors.

Isomeric Covalent Organic Frameworks for High-Efficiency Photocatalytic CO2 Reduction: Substituent Position Effect.

The exploration of covalent organic frameworks (COFs) for high-efficiency photocatalytic CO2 reduction is urgently demanded. Herein, COF-based catalysts are constructed for the selective photoreduction of CO2 to CO via delicately designed isomeric monomers with substituent at the 4,5,9,10- positions (K) or 1,3,6,8-positions (A) of pyrene knots. The distinct substituted regions significantly affect the planarity of pyrene knots, resulting in COFs with different microstructures and photocatalytic activities. While employing a 5 W LED white-light as the light source, the single atomic Co contained A-Py-Bpy-COF-Co showcased a moderate CO evolution rate of 2174.4 µmol g-1 h-1. In sharp contrast, K-Py-Bpy-COF-Co reveals a considerable CO photo-reduction rate of 12 476.4 µmol g-1 h-1 (5.7 times higher than A-Py-Bpy-COF) with a selectivity up to 93.3%. Remarkably, the excellent photocatalytic activity of K-Py-Bpy-COF-Co can be maintained for at least 5 cycles without obvious decay. The distinct photocatalytic properties of the two isomeric COFs can be attributed to the larger steric-hindrance of K-Py-4CHO which enlarges the interlayer distances to inhibit exciton quenching and electron-richer nature of monatomic Co in K-Py-Bpy-COF-Co. This work provides a new protocol to explore COFs with boosted photocatalytic performance via isomeric design from refined modulation of reported COFs.

Efficient photoreduction of CO2 to CO by Co-ZIL-L derived NiCo-OH with ultrathin nanosheet assembled 2D leaf superstructure.

The photocatalytic reduction of CO2 into valuable chemicals and fuels is considered a promising solution to address the energy crisis and environmental challenges. In this work, we introduce a Co-ZIL-L mediated in situ etching and integration process to prepare NiCo-OH with an ultrathin nanosheet-assembled 2D leaf-like superstructure (NiCo-OH UNLS). The resulting catalyst demonstrates excellent photocatalytic performance for CO2 reduction, achieving a CO evolution rate as high as 309.5 mmol g-1 h-1 with a selectivity of 91.0%. Systematic studies reveal that the ultrathin nanosheet structure and 2D leaf-like architecture not only enhance the transfer efficiency of photoexcited electrons but also improve the accessibility of active reaction sites. Additionally, the Ni-Co dual sites in NiCo-OH UNLS accelerate CO2 conversion kinetics by stabilizing the *COOH intermediate, significantly contributing to its high activity. This work offers valuable insights for designing advanced photocatalysts for CO2 conversion.

Sulfur vacancy-rich ZnS on ordered microporous carbon frameworks for efficient photocatalytic CO2 reduction

ZnS has garnered significant attention as a versatile photocatalyst in the field of CO2 reduction. However, its photocatalytic efficiency has been hindered by its high charge recombination rates and sluggish reaction kinetics. Herein, we demonstrate a highly efficient CO2 photoreduction on well-designed S-deficient ZnS nanoparticles within an ordered mesoporous N-doped carbon framework (Vs-ZnS/OMNC) through an in situ thermal treatment strategy. The fs-TA spectrum elucidated that introducing sulfur vacancy (Vs) effectively promoted the separation of photogenerated charges in ZnS/OMNC and significantly improved its reaction kinetics. In situ DRIFTS spectroscopy and DFT calculations revealed that these S vacancies led to charge accumulation on neighboring Zn atoms, enabling effective adsorption and activation of CO2 molecules. Particularly, the vacancy strategy also effectively lowered the energy barrier for forming the key intermediate *COOH. Therefore, the CO evolution rate of Vs-ZnS/OMNC reached 712.1 μmol·g−1·h−1, which is 2.84 times higher than that without sulfur vacancy (250.74 μmol·g−1·h−1). Its CO2 reduction performance surpassed most ZnS-based photocatalysts reported previously. Additionally, the Vs-ZnS/OMNC exhibited outstanding stability without obvious degradation after five reaction cycles. This study provides insights into developing advanced photocatalysts through vacancy defect engineering combined with ordered mesoporous carbon structures.

Boosted photocatalytic CO2 conversion of a Cs2AgBiBr6@Co3O4 composite with high activity and selectivity under low-concentration CO2 and natural sunlight

To explore high-efficiency photocatalysts that can operate under low-concentration CO2 and natural light conditions remains a significant challenge in the field of photocatalysis. Here, we have constructed lead-free Cs2AgBiBr6@Co3O4 (CABB@Co3O4) composites with compact heterogenous interfaces, enhanced CO2 adsorption capability and excellent photoelectronic characteristics. The optimal CABB@Co3O4 heterojunction exhibits nearly 100 % selectivity for visible-light-driven CO2 to CO conversion with the high catalytic efficiency and stability in high-purity and diluted CO2. Importantly, the CABB@Co3O4 photocatalyst is one of a few examples to drive photocatalytic CO2 reduction under the 5 v% CO2 and natural sunlight, exhibiting a linear relationship between CO evolution rate and light intensity. The outstanding photocatalytic performance mainly originates from the suppressed carrier recombination and the decreased energy barrier for the formation of the key *COOH intermediate. This work provides prospective guidance for designing efficient photocatalysts toward CO2 conversion under the actual environmental conditions.

S‐Scheme MnO2/Co3O4 Sugar‐Gourd Nanohybrids with Abundant Oxygen Vacancies for Efficient Visible‐Light‐Driven CO2 Reduction

AbstractConverting CO2 to carbon‐based fuels using solar energy via photocatalysis is a promising approach to boost carbon neutrality. However, the solar‐to‐chemical conversion efficiency is hampered by interconnected multiple factors including insufficient light absorption, low separation efficiency of photogenerated carriers as well as complex and sluggish surface reaction kinetics. Herein, we incorporate MnO2 nanowires and Co3O4 hollow polyhedrons with abundant oxygen vacancies (VO) into MnO2/Co3O4 sugar‐gourd nanohybrids for boosting CO2 photoreduction. The MnO2/Co3O4 nanohybrids not only display strong absorption in the visible–near infrared region, but also facilitate the separation of photogenerated carriers in terms of S‐scheme transfer pathway, supplying abundant electrons for CO2 reduction reaction. Furthermore, the presence of VO enhances the separation efficiency of photogenerated carriers and promotes the chemical adsorption to CO2 molecules. In addition, the interfacial electronic interaction between MnO2 and Co3O4 also contributes to the chemical adsorption and activation to CO2. Owing to the synergy of S‐scheme transfer pathway and VO, the MnO2/Co3O4 hybrids exhibit greatly enhanced photocatalytic activity towards CO2 reduction under the irradiation of visible light in comparison with bare MnO2 and Co3O4, delivering a CO evolution rate of 15.9 umol g−1 h−1 with a 100 % selectivity.

Fluorine-Tuned Carbon-Based Nickel Single-Atom Catalysts for Scalable and Highly Efficient CO2 Electrocatalytic Reduction.

Electrocatalytic CO2 reduction is garnering significant interest due to its potential applications in mitigating CO2 and producing fuel. However, the scaling up of related catalysis is still hindered by several challenges, including the cost of the catalytic materials, low selectivity, small current densities to maintain desirable selectivity. In this study, Fluorine (F) atoms were introduced into an N-doped carbon-supported single nickel (Ni) atom catalyst via facile polymer-assisted pyrolysis. This method not only maintains the high atom utilization efficiency of Ni in a cost-effective and sustainable manner but also effectively manipulates the electronic structure of the active Ni-N4 site through F doping. The catalyst has also been further optimized by controlling the F states, including convalent and semi-ionic states, by adjusting the fluorine sources involved. Consequently, this catalyst with unique structure exhibited comparable electrocatalytic performance for CO2-to-CO conversion, achieving a Faradaic efficiency (FE) of over 99% across a wide potential range and an exceptional CO evolution rate of 9.5 × 104 h-1 at -1.16 V vs reversible hydrogen electrode (RHE). It also delivered a practical current of 400 mA cm-2 while maintaining more than 95% CO FE. Experimental analysis combined with density functional theory (DFT) calculations have also shown that F-doping modifies the electron configuration at the central Ni-N4 sites. This modification lowers the energy barrier for CO2 activation, thereby facilitating the production of the crucial *COOH intermediate.

In-situ carbon-doped poly(triazine imide) modified with silver nanoparticles for synergistic efficient photocatalytic CO2 reduction coupled with biomass refining

Solar-driven CO2 reduction to fuels holds critical importance in addressing climate and energy challenges. However, the practical application faces limitations due to the difficulty in activating CO2, the slow kinetics of the oxidation half-reaction, and the generation of undesired by-products. Herein, we report a functionally-oriented approach for the deliberate fabrication of in-situ carbon-doped poly(triazine imide) modified with silver nanoparticles (Ag NPs) (Ag/C@PTI), aimed at solar-driven CO2 reduction synchronized with xylose oxidation within a single redox cycle. The strategic in-situ carbon doping and the deposition of Ag NPs significantly reduce the bandgap of PTI to 1.60 eV, thereby markedly enhancing charge carrier separation and refining product selectivity. Consequently, the optimally formulated Ag10/C@PTI-10 catalyst demonstrates superior photocatalytic performance in xylose oxidation coupled with CO2 reduction, achieving a xylonic acid yield of 51.4 % and a CO evolution rate of 31.4 μmol g-1h-1. The 13CO2 isotope labeling experiments confirm that a portion of the CO is derived from the xylose conversion process. Moreover, ESR characterization along with capture tests reveal that h+ and ·O2- are pivotal in the photooxidation of xylose to xylonic acid.

Amphiphilic heterojunctions with atomically dispersed copper–alkynyl active units for highly efficient CO2 photoreduction

The efficiency of CO2 photoreduction is limited by slow charge kinetics and the mass transfer of hydrophobic CO2 and H2O over the photocatalyst. Herein, we present a copper–alkynyl bond coordination polymer (CA-CP) with atomically-dispersed copper–alkynyl units (ADCAUs). By incorporating hydrophobic CA-CP with hydrophilic iodine vacancy-rich bismuth oxyhalides (IV-BX), we construct amphiphilic heterojunction photocatalysts (CA-CP/IV-BX) for visible-light-driven CO2 photoreduction. CA-CP/IV-BX achieves excellent stability, 100 % CO selectivity and a CO-evolution rate of 157.6 μmol g−1 h−1 coupled with O2 releasing. Experimental and theoretical calculations elucidate that the ADCAUs favor adsorption and activation of CO2, and have high CO selectivity. Moreover, the amphiphilic janus structure not only ensures the spatial synergy effect of CO2 reduction and H2O oxidation, but also promotes charge separation and proton feeding, boosting CO2 photoreduction activity. This work develops Cu–alkynyl coordination polymer photocatalysts with ADCAUs and provides insights into hydrophobic–hydrophilic biphasic photocatalysts for synergistic CO2 reduction and H2O oxidation.

Hot Electrons Induced by Localized Surface Plasmon Resonance in Ag/g-C3N4 Schottky Junction for Photothermal Catalytic CO2 Reduction.

Converting carbon dioxide (CO2) into high-value-added chemicals using solar energy is a promising approach to reducing carbon dioxide emissions; however, single photocatalysts suffer from quick the recombination of photogenerated electron-hole pairs and poor photoredox ability. Herein, silver (Ag) nanoparticles featuring with localized surface plasmon resonance (LSPR) are combined with g-C3N4 to form a Schottky junction for photothermal catalytic CO2 reduction. The Ag/g-C3N4 exhibits higher photocatalytic CO2 reduction activity under UV-vis light; the CH4 and CO evolution rates are 10.44 and 88.79 µmol·h-1·g-1, respectively. Enhanced photocatalytic CO2 reduction performances are attributed to efficient hot electron transfer in the Ag/g-C3N4 Schottky junction. LSPR-induced hot electrons from Ag nanoparticles improve the local reaction temperature and promote the separation and transfer of photogenerated electron-hole pairs. The charge carrier transfer route was investigated by in situ irradiated X-ray photoelectron spectroscopy (XPS). The three-dimensional finite-difference time-domain (3D-FDTD) method verified the strong electromagnetic field at the interface between Ag and g-C3N4. The photothermal catalytic CO2 reduction pathway of Ag/g-C3N4 was investigated using in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS). This study examines hot electron transfer in the Ag/g-C3N4 Schottky junction and provides a feasible way to design a plasmonic metal/polymer semiconductor Schottky junction for photothermal catalytic CO2 reduction.

Dynamics of co-composting of pineapple harvest and processing residues with poultry litter and compost quality

The production of pineapple generates significant quantities of harvest and processing residues, which are very little used. This study evaluates compost quality using pineapple residues and poultry litter. Five composting treatments were tested, varying following proportions of crown, pineapple processing wastes (PPW), pineapple harvest residue (PHR), and poultry litter (PL). Various parameters were analyzed, including pH, electrical conductivity, CO2 evolution rate, water content, organic carbon, nitrogen compounds, phosphorus, potassium, calcium, magnesium, copper, and zinc. Additionally, the perceptions of producers and processors regarding compost quality were gathered. Results indicated that microbial decomposition increased temperature, pH, CO2 release, and nitrogen content while reducing electrical conductivity and organic carbon. Composts demonstrated favorable characteristics for crop fertilization, with C4 (75% PHR + 25% PL) compost showing the best chemical properties. Producers and processors preferred the color, odor, and structure of C4 (75% PHR + 25% PL) and C5 (56.25% crown + 18.75% PPW + 25% PL) composts. Overall, composting pineapple residues with poultry litter yields composts suitable for plant fertilization, particularly C4 and C5 formulations, offering potential for sustainable waste valorization in agriculture.

Engineering of interfacial electric field by g-C3N4/ZnSnO3 heterojunction for excellent photocatalytic applications

The heterojunction of 2D g-C3N4 thin nanosheets and double-shelled ZnSnO3 nanocubes was prepared via a reliable, convenient, and cost-effective technique to achieve efficient photocatalytic activity. The unique double-layered structure of ZnSnO3 helps to absorb more visible light and provides a shorter diffusion path for charge carriers. The integration of some wrapped g-C3N4 nanosheets to the outer layer of ZnSnO3 increases the multiple active sites and specific surface area (SBET) to boost the photocatalytic reaction. The synergistic effect of heterojunction and oxygen vacancies effectively stimulates the generation and spatial charge separation. Furthermore, as-synthesized 2D/3D heterostructure develops an interfacial electric field that plays an efficient role in charge migration and enhances the redox ability of the material. The degradation efficiency for MB (99.5 %, within 30 mins), TC (98.2 %, within 120 mins), H2 production rate (1799 μmol g−1 h−1) and CO evolution rate (23.6 μmol g−1 h−1) confirms the excellent performance of multifunctional photocatalyst. Additionally, DFT calculations of electronic band structure and density of states are in excellent agreement with experimental results. This work highlights the new perspective on designing suitable nanostructures for photocatalytic applications.

Synthesis of Sulfur Vacancy-Bearing In2S3/CuInS2 Microflower Heterojunctions via a Template-Assisted Strategy and Cation-Exchange Reaction for Photocatalytic CO2 Reduction.

The synthesis of the accurate composition and morphological/structural design of multielement semiconductor materials is considered an effective strategy for obtaining high-performance hybrid photocatalysts. Herein, sulfur vacancy (Vs)-bearing In2S3/CuInS2 microflower heterojunctions (denoted Vs-In2S3/CuInS2) were formed in situ using In2S3 microsphere template-directed synthesis and a metal ion exchange-mediated growth strategy. Photocatalysts with flower-like microspheres can be obtained using hydrothermally synthesized In2S3 microspheres as a template, followed by Ostwald ripening growth during the metal cation exchange of Cu+ and In3+. The optimal heterostructured Vs-In2S3/CuInS2 microflowers exhibited CO and CH4 evolution rates of 80.3 and 11.8 μmol g-1 h-1, respectively, under visible-light irradiation; these values are approximately 4 and 6.8 times higher than those reported for pristine In2S3, respectively. The enhanced photocatalytic performance of the Vs-In2S3/CuInS2 catalysts could be attributed to the synergistic effects of the following factors: (i) the constructed heterojunctions accelerate charge-carrier separation; (ii) the flower-like microspheres exhibit highly uniform morphologies and compositions, which enhance electron transport and light harvesting; and (iii) the vs. may trap excited electrons and, thus, inhibit charge-carrier recombination. This study not only confirms the feasibility of the design of heterostructures on demand, but also presents a simple and efficient strategy to engineer metal sulfide photocatalysts with enhanced photocatalytic performance.

Passivating Defects and Constructing Catalytic Sites on CsPbBr3 with ZnBr2 for Photocatalytic CO2 Reduction.

In recent years, halide perovskites have attracted considerable attention for photocatalytic CO2 reduction. However, the presence of surface defects and the lack of specific catalytic sites for CO2 reduction lead to low photocatalytic performance. In this study, we demonstrate a facile method that post-treats CsPbBr3 with ZnBr2 for photocatalytic CO2 reduction. Our experimental and characterization results show that ZnBr2 has a dual role: the Br- ions in ZnBr2 passivate Br vacancies (VBr) on the CsPbBr3 surface, while Zn2+ cations act as catalytic sites for CO2 reduction. The ZnBr2-CsPbBr3 achieves a photocatalytic CO evolution rate of 57 μmol g-1 h-1, which is nearly three times higher than that of the pristine CsPbBr3. The enhanced performance over ZnBr2-CsPbBr3 is mainly due to the decreased VBr and lower reaction energy barrier for CO2 reduction. This work presents an effective method to simultaneously passivate surface defects and introduce catalytic sites, providing useful guidance for the regulation of perovskite photoelectric properties and the design of efficient photocatalysts.

Flower-like Z-scheme heterostructure of cobalt porphyrin/ZnIn2S4 for boosting photocatalytic solar fuel production

Molecular catalysts have attracted significant attention in photocatalytic CO2 reduction (PCR) due to well-defined structure and exceptional catalytic selectivity. However, they are still limited by recycling challenges and inherent instability. Forming an organic-inorganic composite can address these issues and enhance PCR performance simultaneously. Herein, we developed a flower-like Z-scheme heterojunction of cobalt porphyrin ([meso-tetra(4-sulfonatophenyl)porphyrin], CoTPPS) and ZnIn2S4 (ZIS). The optimized ZIS@CoTPPS exhibited a superior CO evolution rate of 388.26 μmol g−1 h−1, which is 8.96 times of pristine ZIS (43.32 μmol g−1 h−1). The superior PCR activity is contributed by the enhanced light absorption, and photoinduced charge separation facilitated by the Z-scheme structure and the cobalt active sites. Moreover, theoretical calculations confirm the heterojunction relies on a substantial interfacial coupling between the Zn atoms of ZIS and the sulfonic acid groups of CoTPPS through coordination assembly. This investigation affords a useful inspiration for consciously constructing novel ZIS-incorporated atomistic Z-scheme photocatalysts.

Cobalt-based Polymerized Porphyrinic Network for Visible-light-driven CO2 Reduction.

Visible-light-driven conversion of carbon dioxide to valuable compounds and fuels is an important but challenging task due to the inherent stability of the CO2 molecules. Herein, we report a series of cobalt-based polymerized porphyrinic network (PPN) photocatalysts for CO2 reduction with high activity. The introduction of organic groups results in the addition of more conjugated electrons to the networks, thereby altering the molecular orbital levels within the networks. This integration of functional groups effectively adjusts the levels of the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO). The PPN(Co)-NO2 exhibits outstanding performance, with a CO evolution rate of 12 268 μmol/g/h and 85.8% selectivity, surpassing most similar photocatalyst systems. The performance of PPN(Co)-NO2 is also excellent in terms of apparent quantum yield (AQY) for CO production (5.7% at 420 nm). Density functional theory (DFT) calculations, time-resolved photoluminescence (TRPL), and electrochemical tests reveal that the introduction of methyl and nitro groups leads to a narrower energy gap, facilitating a faster charge transfer. The coupling reaction in this study enables the formation of stable C-C bonds, enhancing the structural regulation, active site diversity, and stability of the catalysts for photocatalytic CO2 reduction. This work offers a facile strategy to develop reliable catalysts for efficient CO2 conversion.

Can Biochar Made from Rice Husk Affect Savanna Soils’ pH, Electrical Conductivity, and Soil Respiration?

Biochar is now gaining awareness as a sustainable tool for soil health improvement, boosting carbon (C) storage and the enhancement of nutrient cycling in agricultural soils. This study assesses the effects of biochar on soil respiration, pH, and electrical conductivity (EC) in savanna soils over a 45-day incubation trail in the laboratory. Four different biochar treatments (0, 2, 4, and 6 t/ha) were used in the study. The treatments were established at 26°C, and after 2, 5, and 10 days, the CO2 levels were recorded. After incubation for 0, 5, 10, and 45 days, the EC and pH were assessed. As the rate of application of biochar increased, the rate of CO2 evolution increased as well. During the first two days of incubation, the CO2 evolution rate rose by a value of 129 at 2 t/ha biochar, 146 at 4 t/ha biochar, and 168 ug CO2/g soil/d at 6 t/ha biochar above the 0 t/ha biochar. Following five days of incubation, the amounts of CO2 evolution that were higher than the control were 99 with 2 t/ha, 116 with 4 t/ha, and 120 ug CO2/g soil/d with 6 t/ha of biochar. The increase in CO2 evolution above the control treatment at 10 days of incubation was 61 with 2 t/ha, 79 with 4 t/ha, and 87 ug CO2/g soil/d with 6 t/ha of biochar. Analogously, rising patterns in CO2 emissions were noted. Throughout the whole incubation period, the biochar treatments' soil EC and pH were greater than those of the control treatment. After applying biochar, there were increases in the evolution of CO2, however after 10 days of incubation, the percentage of C evolved from the addition of biochar decreased as the rates of biochar increased. At two t/ha, four t/ha, and six t/ha, the percentage C developed was 1.74 %, 1.66%, and 0.82% of the applied biochar C, respectively. Although the CO2 evolved ratio to the total amount of biochar C typically reduced with increasing biochar rates, this study shows that the addition of biochar increases soil respiration, EC, and pH.