Photoreduction Performance Research Articles

Copper porphyrin modified BiOBr/Bi19S27Br3 for efficient CO2 photoreduction

The insufficient solar light response ability of the photocatalyst, rapid recombination of interface charges, and lack of active sites significantly inhibit the efficiency of photocatalytic CO2 reduction. Addressing these challenges simultaneously is a very challenging task. Herein, an interface engineering coupled surface polarization strategy is proposed to optimize the CO2 photoreduction performance. The copper tetracarboxyphenylporphyrin (CuTCPP) modified BiOBr/Bi19S27Br3 (BBS) heterostructure was developed. The built-in electric field formed between BiOBr and Bi19S27Br3 interfaces induces the effective interfacial charge separation, while the surface polarization of CuTCPP induces the transfer of electrons from the conduction band (CB) of BBS to the CB of CuTCPP. Benefiting from this unique configuration and abundant active sites in CuTCPP, greatly improved photocatalytic CO2 reduction performance can be realized. Without adding cocatalysts and sacrificial agents, the optimized CO generation performance of CuTCPP-BiOBr/Bi19S27Br3 (BBS-CT) is 3.5 times higher than that of BBS. This work provides valuable insights of interface engineering coupled surface polarization strategy for collaborative improve the photocatalytic CO2 reduction performance.

Enhancing CO2 photoreduction efficiency with MXene-modified ZnO@Co3O4 double heterojunction

The photocatalytic reduction of CO2 into energy carriers holds significant industrial appeal, but achieving this process kinetically remains challenging due to the lack of well-designed catalysts. This study presents a novel 2D/3D nanostructured photocatalyst, developed by attaching a few-layer Ti3C2 MXene to polyethylenimine (PEI)-modified ZnO@CO3O4 nanocages, which are derived from a bimetallic zinc-cobalt ZIF. The resulting Mx-PEI-ZnO@Co3O4 catalyst achieved impressive yields of CO and CH4 at 594.37 and 42.67μmol g−1h−1, respectively, without the need for sacrificial agents and photosensitizers, and maintained remarkable stability across multiple cycles. These yields represent the highest performance for ZnO-based catalysts to date, with quantum efficiency at 380 nm reached up to 25.06 %. The unique S-scheme and Mott-Schottky junctions, along with enhanced CO2 adsorption and hydrogen-bond interactions facilitated by the conductive PEI within the Ti3C2/ZnO/Co3O4 double heterojunctions, effectively inhibit electron-hole recombination and significantly enhance CO2 photoreduction performance. This study underscores the combined benefits of double heterojunction engineering, PEI-functionalized CO2 uptake, and MXene co-catalyst integration within a single system, proposing a new approach for designing highly efficient photocatalysts for solar-driven CO2 reduction in energy-efficient fuel production.

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.

Synthesis and characterization of nickel cobaltite–supported film for hexavalent chromium photocatalytic reduction

ABSTRACT Hexavalent chromium (Cr(VI)) is a prevalent and highly toxic pollutant, posing a serious threat to human health and ecosystems. This study addresses this issue by exploring the photocatalytic reduction of Cr(VI) using hydrothermally synthesized nickel cobaltite (NiCo2O4) spinel–supported films. The research fills the gap for efficient visible light photocatalytic materials for Cr(VI) reduction, with the aim to synthesize, characterize, and assess NiCo2O4-supported films’ photocatalytic activity. Synthesis was achieved via a hydrothermal method on fluorine-doped tin oxide (FTO) and titanium dioxide (TiO2) over FTO substrate. The films were characterized using several techniques and their photocatalytic activity was tested under UV-A and visible light, with Cr(VI) concentration monitored periodically up to 240 min. The NiCo2O4/TiO2 film demonstrated superior photoreduction performance under both UV and visible light radiation compared to TiO2 and NiCo2O4, achieving photoreduction of Cr(VI) by 76% under UV light with a rate constant of 5.79 × 10−3 min−1 and 60% under visible light with a rate constant of 4.74 × 10−3 min−1. In conclusion, hydrothermally synthesized NiCo2O4/TiO2 film shows promising photocatalytic performance for Cr(VI) reduction, marking a significant advancement in photocatalysis and water treatment technologies. Future research will focus on stability assessment, synthesis process optimization, and real-world water treatment application.

Near-infrared-responsive sea-urchin-like Ag6Si2O7/Bi19Br3S27 S-scheme heterojunction for efficient CO2 photoreduction

The construction of S-scheme heterojunctions effectively facilitates the spatial separation of photogenerated charge carriers for their involvement in photoreactions. However, the inefficient utilization of solar energy in these heterostructures is often due to unfavorable band-edge positions and suboptimal charge transport dynamics, which result in low photocatalytic efficiency when considering kinetic factors. In this study, sea urchin–like Bi19Br3S27/Ag6Si2O7 S-scheme heterojunctions are fabricated, which exhibit excellent CO2 photoreduction performance under ultraviolet, visible, and near-infrared (NIR) light illumination. Experimental data and density functional theory calculations confirm the S-scheme charge transfer mechanisms, which enable the efficient separation of photogenerated carriers for CO2 reduction. Consequently, the optimized Ag6Si2O7/Bi19Br3S27 heterostructures exhibit superior CO2 photoreduction activity under NIR light irradiation. This approach offers a strategy for designing advanced NIR-light-responsive photocatalysts for efficient CO2 photoreduction.

Surface-Integrating Oxygen Vacancy and CuxO Nanodots Enabling Synergistic Electric Field and Dual Catalytic Sites Boosting CO2 Photoreduction.

High carrier separation efficiency and rapid surface catalytic reaction are crucial for enhancing catalytic CO2 photoreduction reaction. Herein, integrated surface decoration strategy with oxygen vacancies (Ov) and anchoring CuxO (1 < x < 2) nanodots below 10nm is realized on Bi2MoO6 for promoting CO2 photoreduction performance. The charge interaction between Ov and anchored CuxO enables the formation of enhanced internal electric field, which provides a strong driving force for accelerating the separation of photocharge carriers on the surface of Bi2MoO6 (ηsurf ≈71%). They can also cooperatively reduce the surface work function of Bi2MoO6, facilitating the migration of carrier to the surface. Meanwhile, surface-integrated Ov and CuxO nanodots allowing dual catalytic sites strengthens the adsorption and activation CO2 into *CO2 over Bi2MoO6, considerably boosting the progression of CO2 conversion process. In the absence of co-catalyst or sacrificial agent, Bi2MoO6 with Ov and CuxO nanodots achieves a photocatalytic CO generation rate of 12.75µmol g-1 h-1, a remarkable increase of over ≈15 times that of the original counterpart. This work provides a new idea for governing charge movement behaviors and catalytic reaction thermodynamics on the basis of synergistic improvement of electric field and active sites by coupling of the internal defects and external species.

Integrating carbon quantum dots with oxygen vacancy modified nickel-based metal organic frameworks for photocatalytic CO2 reduction to CH4 with approximately 100 % selectivity

Solar-light-driven reduction of CO2 into renewable fuels has great potential in the production of sustainable energy, addressing the energy crisis and environmental problems simultaneously. However, it is a significant challenge to achieve high selectivity for the conversion of CO2 into CH4, which is a type of fuel with a high calorific value. Herein, carbon quantum dots (CQDs) were integrated with an oxygen vacancy modified nickel-based metal organic frameworks (NiMOFs) to form the CQDs-X/NiMOFV series, which exhibited superior performance for CO2 photoreduction into CH4 compared with pure NiMOFs in the presence of hole scavengers under visible light irradiation. The highest yielding rate of CH4 (1 mmol g−1 h−1) and selectivity (97.58 %) were obtained using a CQDs-25/NiMOFV catalyst. Most importantly, in diluted CO2 atmosphere, the yield of CH4 was almost unchanged and the selectivity of CH4 over CQDs-25/NiMOFV was higher than that in pure CO2. The superior performance of CQDs-25/NiMOFV may be attributed to the following two factors: (i) both CQDs and oxygen vacancies facilitate the transmission of electrons to promote the eight-electron reaction producing CH4, and (ii) oxygen vacancies can act as the electron trap to capture the photogenerated electrons to react with adsorbed CO2 on Ni2+. This study offers a valuable strategy for designing efficient photocatalysts to convert CO2 into CH4 with superior selectivity.

Revealing the Effect of Electronic Configuration in Cux Species on CO2 Photoreduction Characteristic Products.

As of the present time, the in-depth study of the structure-activity relationship between electronic configuration and CO2 photoreduction performance is often overlooked. Herein, a series of Cux species modified CeO2 nanodots are constructed in situ by flame spray pyrolysis (FSP) to achieve an efficient photocatalytic CO2-to-C2 conversion with an electron utilization of up to 142.5µmol g-1. Through an in-depth study of the electronic behavior and catalytic pathways, it is found that the Cu0/Cu+ species in the coexistence state of Cu0/Cu+/Cu2+ can optimize the energy band structure, photocurrent stability, and provide a kinetic basis for the active surface catalytic reaction process that requires the conversion of multiple electrons into C2 products, which ultimately enhances the CO2-to-C2H6 photoreduction by 3.8-fold and that for CO2-to-C2H4 photoreduction by 5.2-fold. Besides, the Cu2+ species in the coexistence state of Cu0/Cu+/Cu2+ are able to regulate the electronic behavior and the choice of the catalytic pathway, enabling the transitions between CO2-to-C2H6 and CO2-to-C2H4. This work indicates that electronic configuration optimization is an effective strategy to significantly enhance the CO2 photoreduction performance and provides new ideas for the design and synthesis of high-performance heterostructure photocatalysts.

Room-Temperature Synthesis of Covalently Bridged MOP@TpPa-CH3 Composite Photocatalysts for Artificial Photosynthesis.

The conversion of CO2 into useful chemicals via photocatalysts is a promising strategy for resolving the environmental problems caused by the addition of CO2. Herein, a series of composite photocatalysts MOP@TpPa-CH3 based on MOP-NH2 and TpPa-CH3 through covalent bridging have been prepared via a facile room-temperature evaporation method and employed for photocatalytic CO2 reduction. The photocatalytic performances of MOP@TpPa-CH3 are greater than those of TpPa-CH3 and MOP-NH2, where the CO generation rate of MOP@TpPa-CH3 under 10% CO2 still reaches 119.25 μmol g-1 h-1, which is 2.18 times higher than that under pure CO2 (54.74 μmol g-1 h-1). To investigate the structural factors affecting the photocatalytic activity, MOP@TBPa-CH3 without C═O groups is synthesized, and the photoreduction performance is also evaluated. The controlling experimental results demonstrate that the excellent photoreduction CO2 performance of MOP@TpPa-CH3 in a 10% CO2 atmosphere is due to the presence of C═O groups in TpPa-CH3. This work offers a new design and construction strategy for novel MOP@COF composites.

Radiation reduction modification of sp2 carbon-conjugated covalent organic frameworks for enhanced photocatalytic chromium(VI) removal

A sp2 carbon-conjugated covalent organic framework (BDATN) was modified through γ-ray radiation reduction and subsequent acidification with hydrochloric acid to yield a novel functional COF (named rBDATN-HCl) for Cr(VI) removal. The morphology and structure of rBDATN-HCl were analyzed and identified by SEM, FTIR, XRD and solid-state 13C NMR. It is found that the active functional groups, such as hydroxyl and amide, were introduced into BDATN after radiation reduction and acidification. The prepared rBDATN-HCl demonstrates a photocatalytic reduction removal rate of Cr(VI) above 99% after 60 min of illumination with a solid-liquid ratio of 0.5 mg/mL, showing outstanding performance, which is attributed to the increase of dispersibility and adsorption sites of rBDATN-HCl. In comparison to the cBDATN-HCl synthesized with chemical reduction, rBDATN-HCl exhibits a better photoreduction performance for Cr(VI), demonstrating the advantages of radiation preparation of rBDATN-HCl. It is expected that more functionalized sp2 carbon-conjugated COFs could be obtained by this radiation-induced reduction strategy.

Visible-Light-Driven Reduction of CO2 to CO with Highly Active and Selective Earth-Abundant Metal Porphyrin-Conjugated Organic Polymers.

The field of artificial photosynthesis, which focuses on harnessing solar light for the conversion of CO2 to economically valuable chemical products, remains a captivating area of research. In this study, we developed a series of photocatalysts based on Earth abundant elements (Fe, Co, Ni, Cu, and Zn) incorporated into 2D metalloporphyrin-conjugated organic polymers known as MTBPP-BEPA-COPs. These photocatalysts were utilized for the photoreduction of CO2 employing only H2O as the electron donor, without the need for any sacrificial agents or precious-metal cocatalysts. Remarkably, all of the synthesized MTBPP-BEPA-COPs exhibited an exceptional CO2 photoreduction performance only irradiated by visible light. Particularly, upon optimizing the metal ion coordinated with porphyrin units, ZnTBPP-BEPA-COP outperformed the other MTBPP-BEPA-COPs in terms of photocatalytic activity, achieving an impressive CO reduction yield of 152.18 μmol g-1 after just 4 h of irradiation. The electrostatic potential surfaces calculated by density functional theory suggest the potential involvement of metal centers as binding and catalytic sites for the binding of CO2. The calculated adsorption energy of CO2 with ZnTBPP-BEPA-COP exhibited one of the two smallest values. This may be the reason for the excellent catalytic effect of ZnTBPP-BEPA-COP. Thus, the present study not only demonstrates the potential of porphyrin-based conjugated polymers as highly efficient photocatalysts for CO2 reduction but also offers valuable insights into the rational design of such materials in the future.

Synthesis of strongly interactive FeWO4/BiOCl heterostructures for efficient photoreduction of CO2 and piezo-photodegradation of bisphenol A

Development of multi-functional photocatalysts for CO2 reduction and pollutant elimination is practically significant for solving the environmental problems and energy shortages. In this study, we have immobilized FeWO4 (FWO) nanoparticles on the surface of (001)-facet-exposed BiOCl (BOC) nanosheets through their strong electrostatic interaction to form FWO/BOC heterojunctions. Experimental and theoretical studies corroborate that the FWO/BOC heterojunctions exhibit high-efficiency Z-scheme transfer and separation of photocarriers, and possess excellent photocatalysis for CO2 reduction and bisphenol A (BPA) degradation. Under simulated-sunlight irradiation, the 9 %FWO/BOC heterojunction exhibits a photoreduction performance with CH4/CO yield rates of 4.25/9.41 μmol g−1 h−1 (5 h reaction), which are 3.86/5.26 times higher than those for bare BOC; whereas its photodegradation performance (η(60 min) = 66.8 %, kapp = 0.01755 min−1) is enhanced by 4.3 and 2.7 times compared with that of bare FWO and BOC, respectively. Furthermore, when ultrasonic vibration is simultaneously employed during the simulated-sunlight illumination, the ultrasonic-induced piezoelectric polarization field in BOC nanosheets accelerates the bulk photocarrier separation, resulting in a further improvement in the BPA degradation, and the calculated SF = 1.79 quantifies the degree of enhancement achieved by piezo-photocatalysis collaboration. The introduction of a moderate amount of H2O2 or peroxymonosulfate (PMS) in the reaction solution plays a significant role in promoting the BPA degradation due to the generation of additional •OH and •SO4− reactive species. The mechanisms for photocatalytic CO2 reduction and piezo-photodegradation of BPA catalysis were deeply studied by combining experiments and theory.

Local microenvironment modulation of zirconium-porphyrinic frameworks for CO2 reduction

Solar-powered photocatalysis offers a sustainable strategy to convert carbon dioxide into valuable fuels, which mitigates the energy crisis and the greenhouse effect. Nevertheless, exploring efficient, selective, stable, and environmentally friendly photocatalysts for CO2 reduction continues to meet a significant challenge. Herein, two iron-porphyrinic zirconium-based metal–organic frameworks, Zr6O4(OH)4(FeTCBPP)3 (MOF-526-H) and Zr6O4(OH)4(FeTCBPP-NH2)3 (MOF-526-NH2) were achieved by the integration of the light-harvesting sites and catalytic centers into one phase (FeTCBPP = iron 5,10,15,20-tetra[4-(4′-carboxyphenyl)phenyl]-porphyrin, FeTCBPP-NH2 = iron 5,10,15,20-tetra[4-(4′-carboxyphenyl)-2-aminophenyl]-porphyrin), which were employed as a couple of models for CO2 photoreduction. MOF-526-NH2 exhibited excellent CO2 reduction with a CO yield of 21.2 mmol·g−1 in the absence of any photosensitizer under visible light, which was 4-fold higher than that of MOF-526-H. Additionally, MOF-526-NH2 showed no significant reduction in CO production during the four rounds, indicating that MOF-526-NH2 possessed good stability. The presence of amino groups in MOF-526-NH2 played an important role in adjusting the micro-environment and electronic structure, which was beneficial to CO2 enrichment and light absorption, and thus improved CO2 photoreduction performance. Based on the density functional theory calculations, a possible mechanism of photocatalytic CO2 reduction over porphyrinic MOFs was proposed.

In situ synthesis of g-C3N4/Ag@Ag3PO4 S-scheme heterostructure with tandem ohmic- and d-p bond-junction for photocatalytic reduction of CO2

Low-mass interfacial contacts and poor charge transfer efficiency severely limit the CO2 photoreduction performance of semiconductor heterojunctions. In this work, g-C3N4/Ag@Ag3PO4 S-scheme heterojunction is prepared by an in-situ growth method. The main product for CO2 photoreduction is CO with the selectivity of 97 %. The evolution rate of CO for optimal g-C3N4/Ag@Ag3PO4 heterojunction is 123.8 μmol g−1 h−1, which are 8.3-and 3.4-fold higher than those of pristine Ag3PO4 and g-C3N4, respectively. It is found that Ag3PO4, Ag, and g-C3N4 form strong interacting interfacial structure, in which Ag3PO4 links with Ag nanoparticles through tandem Ohmic contact. More importantly, σ bonds are formed via hybridization of px orbital for C and N with dx2-y2 orbitals of Ag in g-C3N4/Ag@Ag3PO4 S-scheme heterojunction, establishing an atomic-level dx2-y2(Ag)-px(C,N) charge flow highway. This work provides new viewpoints into the design of heterojunction photocatalysts with high-quality interfaces and highlights the insights of charge transfer behavior in regulating the catalytic activity.

Mott–Schottky heterostructural TiO2@Ag@AgBr nanohybrids for efficient photocatalytic degradation of Cr (VI) and enhanced on-site SERS detection

In the study, a novel ternary composite TiO2@Ag@AgBr was successfully prepared by surface modification of complete Ag layer and AgBr particles for photocatalytic degradation of representative heavy metal ions Cr (VI) and on-site Surface-enhanced Raman spectroscopy (SERS) detection of the Cr (VI) reduction process. The Mott–Schottky heterojunction contained structure exhibited remarkable photocatalytic ability for heavy metal ions Cr (VI) by tuning the ratio of Ag and AgBr, which could reduce Cr (VI) ions within 30 min and the reaction rate constant is 0.12 min−1. The remarkable photo-reduction performance is attributed to synergistic effect among the various components: the AgBr decorated on the surface of TiO2@Ag could significantly enhance the absorption of visible light and generate numerous photoexcited electrons and holes. Furthermore, the complete Ag layer was constructed on the TiO2 microspheres surface to form heterojunctions in the photocatalytic system by in-situ deposition of AgNO3. Mott–Schottky junctions formed between AgBr/Ag and Ag/TiO2 interface which could extend the charge transfer pathway and facilitate separation of photoexcited electrons and holes. The plasmonic metal layer of nano Ag could generate significant surface plasmon resonance (SPR) effect which not only enhanced the absorption of visible light but also exhibited remarkable SERS effect for probe molecules. And an amazing detection limit of 1 × 10–10 M could be obtained when using crystal violet (CV) as probe molecules. In addition, the SERS substrates exhibited significant linear relationship between concentration and SERS signal intensity which ensures the accuracy of quantitative analysis and monitoring photoreduction process. The substrates have good cycling stability, enabling it to be reused for SERS detection many times. Thus, the excellent photocatalytic and SERS performance of Mott–Schottky hetero-structural TiO2@Ag@AgBr substrates shows great potential toward rapidly photocatalytic removal Cr (VI) ions and SERS on-site detection reduction process of Cr (VI) in waste water, which is of great significance to environmental protection and ecological restoration.

Perovskite Nanocrystals In Situ Encapsulated in TiO2 Microspheres for Stable CO2 Photoreduction in Water.

Photoreduction of carbon dioxide (CO2) into fuels presents a promising approach to mitigate global warming and energy crises. Halide perovskite nanocrystals (NCs) with prominent optoelectronic properties have triggered substantial attention as photocatalysts but are limited by the charge recombination and instability. Here, we develop stable CsPbBr3/titania microspheres (TMs) by in situ growth of CsPbBr3 NCs inside mesoporous TMs through solid-state sintering, which significantly improves the stability of perovskite NCs, making them applicable in water with efficient CO2 photoreduction performance. Notably, the CsPbBr3/TMs demonstrates a 6.73- and 9.23-fold increase in the rate of CH4 production compared to TMs and CsPbBr3, respectively. The internal electric field facilitates S-scheme charge transfer, enhancing the separation of electron-hole pairs, as evidenced by X-ray photoelectron spectroscopy and electron paramagnetic resonance analysis, which is pivotal for the selective photoreduction of CO2. These insights pave the way for the design of CsPbBr3-based photocatalysts with superior efficiency and stability.

Hollow heterojunction with dual-vacancy engineering to boost photocatalytic performance for photoreduction of CO2 coupled with selective oxidation of benzyl alcohol to benzaldehyde

CO2 photoreduction into chemical fuels is hopeful and sustainable for a carbon–neutral future. Herein, a bifunctional dual-vacancy-modified hollow heterojunction photocatalyst is ingeniously designed for CO2 photoreduction to CO coupling with selective oxidation of benzyl alcohol to benzaldehyde. Synergistic catalysis effect resulted from hollow heterostructures, TiO2 with O vacancies (TiO2-x) and Zn0.3-xCd0.7S with Zn vacancies (ZCS) leads to excellent photoreduction and photoxidation performances. The optimized sample (TiO2-x/ZCS hollow sphere) exhibits highest photocatalytic activity of all the obtained samples. The yields of CO and benzaldehyde are 105 and 323.5 μmol g–1h−1, respectively. The construction of Z-scheme heterojunction realizes the spatial separation of redox reaction sites, and the dual-vacancy distributed on the heterojunction enhance the interfacial reactivity. Additionally, density functional theory calculation and in-situ technology reveal that Zn vacancy in ZCS and O vacancy in TiO2-x function as active sites for the binding and activation of *COOH and *PhCH2O-, respectively, thereby stabilizing the crucial step in the formation of intermediates such as CO and benzaldehyde. This work enhances the utilization of photogenerated carrier, and affords a new opportunity to design hollow heterojunction with dual-vacancy engineering to boost photocatalytic performance for coupling reaction system.

Design of atomically dispersed N-Bi(3+x)+--OV sites in ultrathin Bi2O2CO3 nanosheets for efficient and durable visible-light-driven CO2 reduction

The introduction of oxygen vacancies (OVs) into photocatalysts has proven to be a successful tactic to boost CO2 reduction. However, the challenge lies in acquiring OV sites that are stable in the long term, highly dispersed, and tunable in concentration. Herein, an innovative configuration, referred to as N-Bi(3+x)+--OV, was developed for the model semiconductor Bi2O2CO3 via an in situ anion doping approach. The structure enables the synthetic photocatalyst to exhibit superb CO2 photoreduction performance, with approximately 100% CO selectivity and remarkable long-term stability. Experimental studies and density functional theory (DFT) calculations show that replacing O2- with N3- uniformly in the [Bi2O2]2+ structural unit increases the chemical valence of Bi, elongates nearby Bi─O bonds, releases lattice O, improves CO2 absorption, and decreases the energy barrier for the formation of the critical intermediate *COOH. This study offers new insights and potential opportunities for the development of reliable defect-type semiconductors and their catalytic applications.

Enhanced charge separation of Cu-BTC@CuSe@TiO2 hollow octahedrons for efficient CO2 photoreduction with superior CO selectivity

Solar-driven photocatalytic conversion of CO2 into high-value-added fuels has attracted widespread attention. However, the relatively low conversion efficiency and product yield severely limited photocatalytic applications. In this work, binary Cu-BTC@TiO2 catalysts with adjustable inner cavity were prepared using copper-based metal organic framework (Cu-BTC) octahedrons as substrate via a solvothermal reaction. In this process, the inner Cu-BTC octahedrons can be controllably etched into a hollow octahedral structure in the presence of HF. Subsequently, the Cu-BTC@CuSe@TiO2 hollow octahedrons (HOs) were fabricated by selenization reaction and exhibited various properties such as abundant active sites for CO2 adsorption and reduction reactions, shortened charge transfer distance to prevent electron-hole recombination, and internal reflection/scattering effects to improve solar light utilization. Moreover, the formed dual p-n heterostructures between p-type CuSe and n-type semiconductors (Cu-BTC and TiO2) effectively promote spatial separation and migration of charge carriers. The synergistic effect of these advantages makes the optimized Cu-BTC@CuSe@TiO2 HO catalyst exhibit remarkable CO2 photoreduction performance with a CO production rate of 72.3 μmol h−1 g−1 and near 100 % selectivity. This work opens a new pathway for designing highly active photocatalysts with excellent product selectivity.

Hydrogen‐Bond‐Network Breakdown Boosts Selective CO2 Photoreduction by Suppressing H2 Evolution

AbstractConventional strategies for highly efficient and selective CO2 photoreduction focus on the design of catalysts and cocatalysts. In this study, we discover that hydrogen bond network breakdown in reaction system can suppress H2 evolution, thereby improving CO2 photoreduction performance. Photosensitive poly(ionic liquid)s are designed as photocatalysts owing to their strong hydrogen bonding with solvents. The hydrogen bond strength is tuned by solvent composition, thereby effectively regulating H2 evolution (from 0 to 12.6 mmol g−1 h−1). No H2 is detected after hydrogen bond network breakdown with trichloromethane or tetrachloromethane as additives. CO production rate and selectivity increase to 35.4 mmol g−1 h−1 and 98.9 % with trichloromethane, compared with 0.6 mmol g−1 h−1 and 26.2 %, respectively, without trichloromethane. Raman spectroscopy and theoretical calculations confirm that trichloromethane broke the systemic hydrogen bond network and subsequently suppressed H2 evolution. This hydrogen bond network breakdown strategy may be extended to other catalytic reactions involving H2 evolution.