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The weak bulit-in electric field of BiOBr material is difficult to promote electron-hole separation, resulting in low photocatalytic CO 2 reduction performance. In this work, Ni has been successfully doped in unit cell of BiOBr and increase the unit cell dipole moment of BiOBr along the x, z directions from 0 to 0.04768 and 0.11293 eÅ, respectively. Enhancement of the unit cell dipole moment induces electron spin polarization near the Fermi energy level, which increases the surface potential from 18 mV to 36.2 mV. When the Ni doping ratio is 3 %, a higher carrier separation efficiency is achieved. 3 %Ni-BiOBr has the excellent CO 2 photoreduction performance with CO yield of 378.7 μmolg−1h−1, which is 4.3 times higher than pure BiOBr (86.75 μmolg−1h−1). Briefly, this research work throws light on enhancing built-in electric field by increasing unit cell dipole moment and inducing spin polarization for improving the photocatalytic performance. [Display omitted] • Ni doping into BiOBr increases the dipole moment and induce the spin polarization to enhance built-in electric field. • 3 %Ni-BiOBr CO 2 photoreduction performance with CO yield is 378.7 μmolg−1h−1. • The CO 2 photoreduction mechanism of 3 %Ni-BiOBr with enhanced electric field is proposed. [ABSTRACT FROM AUTHOR]

A simple photodeposition method is used to prepare Cu and Au nanoparticles modified TiO 2 nanocomposites. The phase composition of the catalyst is determined by x-ray diffraction. The mutual synergistic effects of Cu and Au are analyzed using x-ray photoelectron spectroscopy, photoluminescence spectroscopy and UV diffuse reflectance spectroscopy. The results indicate that the TiO 2 is anatase structure with hollow cubic morphology, which enhances the utilization of visible light and improves the photocatalytic performance compared with P25. The Cu 0.7 Au 0.3 /TiO 2 has the highest carrier separation efficiency and the best photocatalytic performance with a CO yield of 6.08 umol g−1 h−1, which is about four times higher than that of TiO 2 (1.56 umol g−1 h−1). The aforementioned results indicate that the photocatalytic activity for CO 2 reduction is greatly enhanced by the addition of modest quantities of Cu and Au NPs. During the photocatalytic process, the presence of Au NPs absorbs visible light and modulates the surface structure of electrons, while Cu serves as an electron sink, hence promoting efficient separation of electron-hole pairs. Utilizing the distinct benefits of bimetal and their robust interactions is a viable and efficacious approach for boosting the photocatalytic activity. • The Cu and Au NPs loaded hollow cubic TiO 2 structures were constructed. • The electron hole separation efficiency were improved and the interfacial charge transfer resistance was reduced. • The performance of photocatalytic CO 2 to CO was 6.08 umol g−1 h−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of Bi in benzene-ring-grafted g-C 3 N 4 were prepared by a facile method. • The introduction of the benzene-ring enhances the charge separation efficiency. • A CO yield rate of 8.17 μmol/g·h was achieved via this strategy. Graphitic carbon nitride (g-C 3 N 4) holds a prominent position in the field of photocatalysis and represents one of the most promising non-metallic catalysts at present. However, its inherent defects undermine its photocatalytic activity, thus limiting its practical applications. To address this issue, we employed transition metal bismuth spheres, which were dispersed and anchored on benzene-ring-grafted porous g-C 3 N 4 nanosheets, for the photocatalytic reduction of CO 2 via a simple solvothermal synthesis method. The experimental results revealed that Bi-BCN-0.2 exhibited the highest photocatalytic CO 2 reduction, yielding 8.17 μmol/(g·h) of CO, which was 21 times greater than CN (0.39 μmol/(g·h)) and 8.5 times greater than BCN (0.95 μmol/(g·h)). Through relevant characterization, we found that the introduction of benzene rings in the CN skeleton resulted in an expansion of π-electron delocalization, leading to improved the efficiency of charge separation upon photoexcitation. Additionally, the further loading of Bi sphere co-catalysts, forming Schottky junctions, effectively inhibited the recombination of photogenerated electron-hole pairs and promoted photogenerated charge transfer. Furthermore, the SPR (surface plasmon resonance) effect enhanced the light harvesting ability. These modifications collectively contributed to enhancing the photocatalytic activity of g-C 3 N 4 and introduced a novel approach for utilizing g-C 3 N 4 in the photocatalytic reduction of CO 2. [ABSTRACT FROM AUTHOR]

• The heterostructural 2D/1D BiOBr/CdS composites were prepared by hydrothermal method. • The composites display more effective charge separation and migration. • The composites present a high CO production rate of 13.6 μmol g−1. Herein, a generalizable strategy using the solvothermal process to obtain the heterostructural composites between BiOBr nanosheet and CdS nanorods is presented. Using a facile hydrothermal method, the CdS nanorods were anchored onto BiOBr nanosheets with average scales ranging from 10 to 500 nm to build up the heterostructure. The improvement of the efficiency of charge separation through the construction of 2D/1D heterojunction was confirmed by SEM, TEM, XPS, photocurrent, and AC impedance. CO 2 photoreduction was employed to study the photocatalytic activities of the as prepared composites. The heterostructural BiOBr/CdS composites owned better activity than both the pure BiOBr nanosheets and pure CdS nanorods. Most significantly, the yield of CO during photocatalytic reduction reaction with BiOBr/CdS-5% catalyst was measured to be 13.6 μmol g−1, which was 1.8 times larger than that with BiOBr nanosheets and 6.4 times larger than that with CdS nanorods during 3 h simulative sunlight exposure. The optimized photocatalytic property of heterostructural BiOBr/CdS-5% composite could be attributed to the wide sunlight response range, large specific surface area, and effective separation of photoelectrons-holes from the heterostructure between BiOBr nanosheets and CdS nanorods. [ABSTRACT FROM AUTHOR]

• BiOBr nanosheets modified with NH 2 -UiO-66 were successfully synthesized. • 1 % BiOBr/NH 2 -UiO-66 has good reducing properties with a CO yield of 9.19 µmolg-1h−1. • The BiOBr/NH 2 -UiO-66 type II heterojunction was constructed. As a typical semiconductor catalyst, BiOBr has an advisable bandgap, superior light absorption properties, and a unique laminated structure. However, the slow electron-hole separation rate results in poor CO 2 reduction performance. To enhance the photocatalytic efficiency of BiOBr, this study constructs BiOBr heterojunctions with Lewis basic groups by loading NH 2 -UiO-66 on BiOBr. The BiOBr/NH 2 -UiO-66 heterojunction have been built and possess stronger light response, larger specific surface area and electron-hole separation efficiency compared to pure BiOBr and NH 2 -UiO-66. The optimal BiOBr/NH 2 -UiO-66 displays that the CO yield is 9.19 μmol g-1h−1, which is 4 times higher than pure BiOBr. [ABSTRACT FROM AUTHOR]

• Constructed BiOBr/In 2 O 3 II-type heterojunction composites using a simple hydrothermal method. • BiOBr/In 2 O 3 heterojunction interfaces facilitate electron transport. • BiOBr/In 2 O 3 –2 % exhibits good selectivity for reduction with a CO 2 reduction energy of 9.81 μmol·g−1·h−1. The advancement of catalysts featuring high carrier separation efficiency enhances photocatalytic reduction performance. This study employed a simple hydrothermal method to anchor In 2 O 3 nanoparticles onto the surface of two-dimensional BiOBr nanosheets, constructing a type-II heterostructure that improves the photocatalytic reduction capability. The composites of 0D/2D In 2 O 3 /BiOBr underwent XPS, TPR, and MS characterization, validating the formation of a type-II heterostructure. In 2 O 3 functioned as an electron-aggregating active site that extracted photogenerated electrons from the surface of BiOBr. As a result, the efficiency of charge separation is markedly increased. The results of the CO 2 reduction test indicate that In 2 O 3 -modified BiOBr exhibits superior photocatalytic activity compared to pure BiOBr, with 2 % In 2 O 3 /BiOBr exhibiting the highest reduction performance. The CO yield achieved was 9.81 µmol·g−1·h−1, which is 5.33 times higher than that of pure BiOBr and 42.65 times higher than that of pure In 2 O 3. These findings offer future potential for the application of In 2 O 3 as an electron-accumulating material to enable the photocatalytic reduction of CO 2. [ABSTRACT FROM AUTHOR]

• The P-doped BiOBr photocatalysts were synthesized through a one-step hydrothermal method. • Broadening of the light absorption edge of BiOBr by P doping, fine-tuning of the band gap of BiOBr, and enhancement of photogenerated electron and hole mobility. • The optimal photocatalytic reduction of CO 2 to produce CO at a rate of 9.13 µmolg−1h−1 was 3.3 times higher than the pure BiOBr catalyst. • Providing a simple method for photocatalytic CO 2 reduction in nonmetallic P-doped semiconductors. The photocatalytic CO 2 reduction efficiency of BiOBr is constrained by its insufficient ability to effectively absorb visible light, as well as its rapid photogenerated electron-hole complexation. Modulating the band gap and charge transfer kinetics of photocatalysts through heteroatom doping is an effective solution. P-doped BiOBr photocatalysts were synthesized through a one-step hydrothermal method to promote the photocatalytic reduction of CO 2 in this investigation. The photocatalytic reduction of CO 2 to CO using an 8 % P-BiOBr catalyst achieved a rate of 9.13 µmolg−1h−1, which is 3.3 times greater than that observed with the pure BiOBr catalyst. XPS, UV-Vis DRS and Mott-Schottky analyses revealed that P-BiOBr had a narrower forbidden bandwidth and a more negative conduction band, which improved the absorption of visible light and the reduction ability of CO 2. Furthermore, The transient photocurrent response, electrochemical impedance spectroscopy (EIS), and photoluminescence (PL) spectra signify that the doping of phosphorus (P) enhances the separation and mobility of the carriers generated by light in BiOBr. This research offers a straightforward approach for doping with P, which enhances photocatalytic reduction of CO 2 by semiconductor. [ABSTRACT FROM AUTHOR]

• Ultrafine Pt nanoparticles were loaded on the surface of TiO 2 nanoparticles with oxygen-rich vacancies by photoreduction method. • Synergistic effect of metal sites and oxygen vacancies was proposed. • Synergy effect greatly enhanced the CO 2 photoreduction performance. • Synergy effect ensures the long-term stability of the catalyst. In this work, TiO 2 NPs (NPs) with abundant defects were successfully prepared as a substrate by photochemical method to load highly dispersed Pt NPs, focusing on the synergy between metal sites and oxygen vacancies for the enhancement of CO 2 photoreduction performance and stability. As expected, H 2 -Pt/TiVo-UV exhibited excellent photocatalytic efficiency, with a photoreduction selectivity of up to 92.9 % for CO 2 and a total electron yield of 382.4 μmol g−1 h−1. More importantly, H 2 -Pt/TiVo-UV activity decreased by only 6.8 % after a continuous reaction of up to 24 h. TiO 2 NPs with abundant defects promote the migration of photogenerated electrons. The highly dispersed Pt NPs acted as electron traps, promoting photogenerated carrier separation. Meanwhile, the synergy between metal sites and oxygen vacancies enhances the adsorption capacity to the reactants. The combined effect of these three factors provides the driving force for the improved photocatalytic performance. This work provides insight into the efficient use of noble metal catalysts. [ABSTRACT FROM AUTHOR]

In this work, the BiOCl/In 2 O 3 catalyst for the photocatalytic reduction of CO 2 was successfully prepared by the hydrothermal method and the type II heterojunction was successfully constructed. The photocatalytic activity of the complex catalyst for the photocatalytic reduction of CO 2 was investigated. The results show that the photocatalytic yield of the BiOCl/In 2 O 3 composite to CO is 6.9 µmolg−1h−1, which is 3.6 and 35 times that of BiOCl nanosheets and In 2 O 3 , respectively. The BiOCl/In 2 O 3 composite photocatalyst has better visible light absorption and better charge separation efficiency. The significant improvement in the photocatalytic performance can be attributed to the improvement in the visible light absorption range and the reduced band gap, which can increase the production of photogenerated electrons and thus facilitate the reaction of CO 2 reduction to CO. [Display omitted] • Two-dimensional BiOCl nanosheets modified with In 2 O 3 nanoparticles were successfully synthesized. • 1 %BiOCl/In 2 O 3 exhibits good selectivity for reduction with a CO 2 reduction energy of 6.9 µmolg−1h−1. • BiOCl/In 2 O 3 composites have significantly enhanced CO 2 to CO activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hybridization strategy to address CO 2 adsorption and photogenerated carrier separation simultaneously. • The CO evolution of BN-15 reached 121.8 μmol g−1 h−1, which is 5 times higher than pure BiOBr. • A possible mechanism of photoreduction of CO 2 by hybrid material is proposed. The low electron-hole separation efficiency and poor CO 2 adsorption of BiOBr limit its photoreduction CO 2 performance. In this work, BiOBr was hybridized with Ni-MOF, it shows that the E ads of BiOBr decreases from −0.36 eV to −1.73 eV, and the Gibbs free energy of CO 2 adsorption decreases from 0.12 eV to −1.25 eV. In addition, the PL and TPR results reveal that the hybridization strategy accelerates the electron-hole separation rates. The CO evolution of BiOBr/Ni-MOF is 121.8 μmol g−1 h−1 when the amount of Ni-MOF is 15%, which is 5 and 7.2 times higher than BiOBr and Ni-MOF, respectively. Briefly, the CO 2 adsorption and photogenerated carrier separation of inorganic materials can be improved by organic–inorganic hybridization strategy, which inspires a new direction for the design of high-performance catalysts. [ABSTRACT FROM AUTHOR]

In this work, we formed C 3 N 4 /Cu 2 O (CN/Cu 2 O) composite photocatalysts by growing Cu 2 O in situ on C 3 N 4 (CN) via oil bath method. The heterojunction between CN and Cu 2 O can broaden the light absorption range, enhance the light absorption, reduce the internal resistance to electron transfer and improve the efficiency of photogenerated electron-hole separation, thus enhancing the photocatalytic performance of carbon nitride. The photocatalytic performance of the synthesized CN/Cu 2 O composite photocatalysts was also tested. The test results showed that the best photocatalytic performance of CN/Cu 2 O-60 was achieved at 2.27 μmolg−1h−1 under 3 h xenon lamp irradiation, which was 8.5 and 5.7 times that of pure CN and pure Cu 2 O, respectively. [Display omitted] • CN/Cu 2 O improves electron-hole separation efficiency and spectral response range. • The photoreduction CO 2 performance reached 2.23 μmolg−1h−1, which is 8.3 times higher than that of pure C 3 N 4. • A possible mechanism of photoreduction CO 2 is proposed. [ABSTRACT FROM AUTHOR]

• The heterostructural 2D/2D BiOBr/Zn(OH) 2 composite was prepared by direct precipitation polymerization. • The composite displays more effective charge separation and migration. • The composite presents a high CO production of 16.21 μmol g−1. For the sake of enhancing the photocatalytic performance of BiOBr, 2D Zn(OH) 2 nanosheets were introduced on 2D BiOBr nanosheets to construct a 2D heterosturcture in BiOBr/Zn(OH) 2 composites by direct precipitation polymerization. After depositing Zn(OH) 2 , the specific surface areas of BiOBr/Zn(OH) 2 composites were improved, which resulted in more active sites. Meanwhile, the synergistic action between Zn(OH) 2 and BiOBr can adjust the band-gap, enhancing the light absorption and reducing the charge transfer resistance. BiOBr/Zn(OH) 2 composites possessed the better separation efficiency of photogenerated carriers. Meanwhile, the results showed that the ability of photocatalytic CO 2 reduction was improved. Under 3 h simulated sunlight irradiation, BiOBr/Zn(OH) 2 –10% showed the highest performance of photocatalytic CO 2 reduction, and the total output of photocatalytic reduction product CO was 16.21 μmol g−1, which is 2.2 times than that of BiOBr. [ABSTRACT FROM AUTHOR]

The results indicate that Zn component can reduce the charge transfer resistance of Al-based LDHs, which leads to a higher photo-generated current density, thus achieving a high CO 2 reduction performance. [Display omitted] • The Zn component can reduce the charge transfer resistance of Al-based LDHs. • The ZnAl-LDH presents a higher yield and selectivity of CO product than MgAl-LDH and NiAl-LDH. • The strategy of regulating divalent metal species can construct advanced LDH-based photocatalyts. Photocatalysis is a potential technology to reduce CO 2 greenhouse gases. Layered double hydroxides (LDHs) are promising photocatalysts due to good catalytic activity, low synthesis cost, and large-scale preparation. However, their CO selectivity in photocatalytic CO 2 reduction is still unsatisfactory. Herein, we have systematically studied the effects of different divalent metal species (e.g. , Mg2+, Ni2+, and Zn2+) on the CO selectivity in aluminum-based LDHs. The results indicate that ZnAl-LDH can negatively shift the conduction band to obtain a large driving power for CO 2 reduction to CO, which much improves the CO selectivity. In addition, the ZnAl-LDH also reduces the charge transfer resistance leading to a higher photo-generated current density, thus achieving a high CO 2 reduction performance. Specifically, ZnAl-LDH presents a better CO selectivity of 72.8 % and a higher CO yield of 1.58 μmol·g−1·h−1, than MgAl-LDH (66.2 %, 0.96 μmol·g−1·h−1) and NiAl-LDH (59.8 %, 1.01 μmol·g−1·h−1). This study provides a feasible strategy to improve the selectivity of CO photocatalytic reduction of CO 2 by regulating divalent metal species in aluminum-based layered double hydroxides. [ABSTRACT FROM AUTHOR]

• BiOBr/CoAl-LDH heterojunctions with suppressed Z-axis growth were prepared. • The closely contact between heterojunctions were proved. • A highly CO 2 photoreduction performance was achieved. • The deep mechanism during the photocatalytic reaction was investigated. Due to the massive usage of fossil fuels, the carbon dioxide content in the atmosphere is increasing year by year. Meanwhile, the CO 2 photoreduction has been widely researched and regarded as a promising method to utilize the CO 2. BiOBr has good photocatalytic activity as a suitable photocatalyst. However, the photocatalytic performance is still unsatisfactory, and the product of CO 2 photocatalytic reduction has a large proportion of CO instead of CH 4. Therefore, in this paper, we prepare ultrathin CoAl-LDH by inhibiting Z-axis growth and load ultrathin CoAl-LDH on BiOBr to construct heterojunction to improve the photocatalytic efficiency of BiOBr and regulate the selectivity of the products. It was found that the loading of ultrathin CoAl-LDH helps to improve the photogenerated electron-hole pair separation ability and photogenerated carrier transport ability, thus improving the photocatalytic performance. At the same time, the loading of ultrathin CoAl-LDH helps to convert the photocatalytic CO 2 reduction product from CO to CH 4. After the gradient study experiment on the dosage of ultrathin CoAl-LDH, it was found that the best effect was achieved at the dosage of 10 mL of ultrathin CoAl-LDH colloidal solution, and the CO yield rate was 4.096 μmol·g−1·h−1 and CH 4 yield rate was 4.174 μmol·g−1·h−1. Meanwhile, the CH 4 selectivity will reach 46% of the product. In this work, we offer a novel regulation strategy for selectivity improvement of CO 2 photocatalytic reduction, which can be assigned to the moderated ultrathin CoAl-LDH loading, thus enhance the selectivity of CO 2 to CH 4. [ABSTRACT FROM AUTHOR]

A heterostructured ZnAl-LDH@ZIF-8 hybrid largely enhances its photocatalytic CO 2 reduction ability. [Display omitted] • A novel photocatalyst/adsorbent hybrid of ZnAl-LDH@ZIF-8 was prepared. • The hybrid showed a high visible-light-response activity and high selectivity for CO 2 reduction. • The mechanism on photocatalysis and adsorption of ZnAl-LDH@ZIF-8 hybrid was revealed. • The structure–activity relationship of ZnAl-LDH@ZIF-8 hybrid was studied in detail. • The photocatalytic performance of ZnAl-LDH@ZIF-8 hybrid was 7.0 times higher than ZnAl-LDH. Artificial photocatalytic technology is widely used to reduce atmospheric CO 2 and convert it into a series of available carbon containing fuels. Among a series of photocatalysts, LDH (layered double hydroxides) and ZIF (zeolitic imidazolate framework) materials have attracted interest of many researchers because of their special physical and chemical properties. In this work, we center on the technical problems of LDH and ZIF in photocatalytic CO 2 reduction process, we combined the respective advantages of LDH and ZIF materials to design a new heterostructured ZnAl-LDH@ZIF-8 hybrid photocatalyst/adsorbent, which had a wide range of visible light response, high activity and high selectivity. Through a series of structural characterizations, the results revealed that ZnAl-LDH as a catalyst was excited and produced photoelectric charge under the excitation of sunlight. Meanwhile, the CO 2 adsorbed on the catalyst surface was reduced to CO by photogenerated electrons which were migrated from ZnAl-LDH to ZIF-8 surface. The ZnAl-LDH@ZIF-8 hybrid showed a remarkable photocatalytic CO 2 conversion of 9.03 μmol·g−1·h−1 and a high selectivity of 97.77%. In addition, the effect on the excitation transfer of photoelectric charge and photocatalytic CO production of interaction between ZnAl-LDH and ZIF-8 were studied, and the relationships among catalyst compositions, surface structures, photoelectric properties, and catalytic performances were clarified. This research supplies a significant method for the construction and development of new type photocatalyst/adsorbent heterostructure, and provides new viewpoints and technical support for in-depth understanding of photocatalytic CO 2 reduction. [ABSTRACT FROM AUTHOR]