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As a low-cost, low toxicity and metal-free catalyst with strong light absorption, graphitic carbon nitride (g-C3N4)-based materials have gained wide attention for efficient H2O2 photocatalysis. However, further investigation regarding the charge transfer process and reaction mechanism of H2O2 photoproduction remains to be completed. In this work, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTDA) modified g-C3N4 is synthesized through a facile one-step dehydration process, and the H2O2 photoproduction could reach 22.5 μmol within 8 hours. The proposed structure of g-BTDA is confirmed by FTIR, XPS and SEM studies. The transient absorption reveals a 20.88 ps charge transfer process caused by the electron withdrawing ability of the C＝O group, and a 2-electron oxygen reduction pathway is proposed. Our work represents a new strategy for efficient H2O2 photoproduction using easily acquired materials with future application potential. [ABSTRACT FROM AUTHOR]

Defects engineering is significant for photocatalytic environment remediation. To this end, visible‐light‐driven α‐Fe2O3/ZrO2‐x S‐scheme heterojunction photocatalysts with optimal oxygen vacancy (Ov) defects are successfully synthesized via a two‐step method. Compared with pristine UiO‐66‐NH2‐derived ZrO2‐x and α‐Fe2O3, the heterojunction photocatalysts exhibit a wider range of visible light response and higher efficiency in separating photogenerated electron–hole pairs. Among them, the 5% α‐Fe2O3/ZrO2‐x sample shows the best photocatalytic performance to the degradation of tetracycline (TC) (89.3%), in which the pseudo‐first‐order kinetic rate constants are 8.20 and 16.75 times that of pristine ZrO2‐x and α‐Fe2O3, respectively. The outstanding photocatalytic degradation efficiency can be attributed to both the narrow‐bandgap ZrO2‐x with visible light response and the formation of α‐Fe2O3/ZrO2‐x S‐scheme heterojunctions. During the formation of heterojunctions, the concentration of oxygen vacancies (Ov) at the interface of α‐Fe2O3/ZrO2‐xdecreases monotonically with the increasing loading of α‐Fe2O3, thereby altering the electronic structure of the photocatalyst and forming the heterojunction firmly. In addition, the high stability implies the potential applications in fields of environment. [ABSTRACT FROM AUTHOR]

Nanoformulations with endogenous/exogenous stimulus‐responsive characteristics show great potential in tumor cell elimination with minimal adverse effects and high precision. Herein, an intelligent nanotheranostic platform (denoted as TPZ@Cu‐SnS2‐x/PLL) for tumor microenvironment (TME) and near‐infrared light (NIR) activated tumor‐specific therapy is constructed. Copper (Cu) doping and the resulting sulfur vacancies can not only improve the response range of visible light but also improve the separation efficiency of photogenerated carriers and increase the carrier density, resulting in the ideal photothermal and photodynamic performance. Density functional theory calculations revealed that the introduction of Cu and resulting sulfur vacancies can induce electron redistribution, achieving favorable photogenerated electrons. After entering cells through endocytosis, the TPZ@Cu‐SnS2‐x/PLL nanocomposites show the pH responsivity property for the release of the TPZ selectively within the acidic TME, and the released Cu2+ can first interact with local glutathione (GSH) to deplete GSH with the production of Cu+. Subsequently, the Cu+‐mediated Fenton‐like reaction can decompose local hydrogen peroxide into hydroxyl radicals, which can also be promoted by hyperthermia derived from the photothermal effect for tumor cell apoptosis. The integration of photoacoustic/computed tomography imaging‐guided NIR phototherapy, TPZ‐induced chemotherapy, and GSH‐elimination/hyperthermia enhanced chemodynamic therapy results in synergistic therapeutic outcomes without obvious systemic toxicity in vivo. [ABSTRACT FROM AUTHOR]

Mesoporous TiO 2 nanospheres with engineered surface defects are fabricated through surfactant-mediated self-assembly solvothermal approach combined with surface hydrogenation, which exhibit excellent solar-driven photocatalytic hydrogen evolution, due to surface defects induced charge imbalance improving charge separation, and unique spherical mesoporous structure supplying adequate surface-active sites and facilitating mass transfer. [Display omitted] • Surface defects induced charge imbalance promote charge separation. • Mesoporous TiO 2 nanospheres with engineered surface defects are fabricated. • Nanoscale mesoporous spheres have closed packing and low surface energy. • It exhibits excellent solar-driven photocatalytic H 2 evolution and high stability. • Surface defects and mesostructure favor charge separation and mass transfer. Low charge separation efficiency of semiconductor materials is the main obstacle for high-performance photocatalyst. Herein, we report surface defects engineered uniform mesoporous TiO 2 nanospheres (DMTNSs) through surfactant-mediated self-assembly solvothermal approach combined with hydrogenation strategy to promote charge separation. The surface defects induced charge imbalance result in the formation of built-in field, which can promote photogenerated charge separation efficiently and be confirmed by experimental and density functional theory (DFT) calculations. Under AM 1.5G irradiation, the photocatalytic hydrogen evolution of DMTNSs is ~3.34 mmol h−1 g−1, almost 3.5 times higher than that of pristine non-defective TiO 2 nanospheres (0.97 mmol h−1 g−1), due to the engineered surface defects narrowing the bandgap (~3.01 eV) and inducing charge imbalance to boost spatial charge separation and extend visible-light response. The defect induced charge imbalance strategy opens a new valuable perspective for fabricating other high-efficient oxide photocatalysts. [ABSTRACT FROM AUTHOR]

Oxygen-defective Bi 2 MoO 6 /g-C 3 N 4 hollow tubulars S-scheme heterojunctions are fabricated by hydrothermal and calcination methods and show excellent photocatalytic performance. The S-Scheme heterojunction accelerates the effective charge separation and transfer by internal electric field (IEF) and energy band bending at the interface, thus improving the photocatalytic performance. [Display omitted] Novel S-scheme heterojunction photocatalysts of bismuth molybdate/hollow tube graphite carbon nitride (Bi 2 MoO 6 SOVs/g-C 3 N 4) containing surface defects (SOVs) were prepared by calcination and hydrothermal methods. The hollow tubular structure of g-C 3 N 4 facilitates the enhancement of multiple reflection and scattering of light, and also have a larger range of specific surface areas and more reactive sites, which promotes carrier separation and thus improves photocatalytic performance. The introduction of SOVs to bismuth molybdate not only reduces the band gap of bismuth molybdate, but also promotes the separation of charges. The optimized Bi 2 MoO 6 SOVs/TCN photocatalyst has a hydrogen production efficiency of 2.29 mmol h−1 g−1. It also shows high photocatalytic degradation property of tetracycline and bisphenol A in water, up to 97.3 % and 98.9 %, respectively. Meanwhile, the transfer mechanism of photogenerated charges in S-scheme heterojunctions can be verified by electron paramagnetic resonance and in situ irradiated x-ray photoelectron spectroscopy electron paramagnetic resonance, which accelerated the separation and transfer of photogenerated charge by energy band bending at the interface and internal electric field. This rational structural design strategy provides a new development idea for building high-performance S-scheme heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

Ag-polydopamine nanoparticles co-decorated defective mesoporous carbon nitride assembly with wide spectrum response is fabricated, which exhibits robust photothermal-photocatalytic H 2 production, due to Ag-PDA not only extends the light absorption of DCN, but also forms an efficient Z-scheme charge transfer path with DCN, enabling fast electron transfer. [Display omitted] • Ag-polydopamine nanoparticles co-decorated defective mesoporous carbon nitride assemblies are fabricated. • Ag-polydopamine nanoparticles co-decorated promote efficient charge transfer. • Small-sized Ag nanoparticles as efficient cocatalysts enables efficient charge separation. • Ag-polydopamine extends photoabsorption and produces obvious photothermal effect to improve catalyze activity. • The formation of Z-scheme charge transfer mechanism favors spatial charge separation. Ag-polydopamine nanoparticles co-decorated defective mesoporous carbon nitride nanosheets assemblies (Ag-PDA/DCN) with wide spectrum responseare fabricated. The Ag-PDA/DCN assemblies exhibit excellent photocatalytic hydrogen production performance. The visible light and near-infrared light driven photocatalytic hydrogen evolution rate is up to 3840 μmol h−1 g−1, which is 20 and 7 times higher than those of DCN and PDA/DCN, respectively. This is mainly because the Ag-polydopamine nanoparticles not only form an efficient carrier transport path and realize fast electron transport, but also further extend the photoresponse of DCN, resulting in an obvious photothermal effect to further improve the photocatalytic activity. More importantly, the formed Ag nanoparticles by the low-temperature photodeposition method is smaller in size and better in dispersibility. Ag nanoparticles act as a co-catalyst in Ag-PDA/DCN, which can effectively separate the spatially photogenerated charge carriers. Compared to three systems with different Ag decoration positions, Ag-PDA/DCN with Z-scheme charge transfer mechanism is more favorable for promoting photocatalytic performance. This co-decorated strategy provides a new idea for developing low-cost Pt-free photocatalysts for solar energy conversion. [ABSTRACT FROM AUTHOR]

Polydopamine/defective ultrathin mesoporous graphitic carbon nitride Z-scheme organic assembly is fabricated via N -vacancy defects and π-π interactions, which exhibits robust photocatalytic H 2 production and contaminant degradation, due to the direct Z-scheme charge transfer mechanism to realize efficient spatial charge separation, and the enhanced photothermal effect to promote the photocatalytic reaction. [Display omitted] • Polydopamine/defective ultrathin mesoporous graphitic carbon nitride organic assemblies are fabricated. • N -vacancy and π-π interactions provide strong connection and fast charge transfer. • Z-scheme structure enables efficient of photogenerated charges separation. • Polydopamine extends photoabsorption and produces photothermal effect to improve catalyze activity. Polydopamine/defective ultrathin mesoporous graphitic carbon nitride (PDA/DCN) Z-scheme organic assembly is fabricated through high-temperature surface hydrogenation and ultrasonic freeze-dried strategies. PDA could be anchored on the surface of DCN with adequate N -vacancy defects firmly via π-π interactions, forming Z-scheme heterogenous structure for promoting charge separation. The visible and near-infrared light driven photocatalytic hydrogen evolution rate is up to 3420 μmol h−1 g−1, and the removal ratio of organic contaminant methylene blue is up to 98% within 70 min, which is several times higher than that of pristine graphitic carbon nitride and DCN. The important reason is the defects of DCN not only enhance the interaction with PDA, but also make the obvious polarized inbuilt electric field, and lead to Z-scheme structure for effective charge separation and rapid transfer, which is also confirmed by density functional theory (DFT) calculations. In addition, PDA extends the photoresponse to the near-infrared region and induces obvious photothermal effect to increase the reaction rate of the photocatalytic system. The efficient photothermal conversion of PDA/DCN should be another reason for the enhanced photocatalytic performance. [ABSTRACT FROM AUTHOR]

Ni/ZnIn 2 S 4 nanosheet assembly with sulfur vacancy and Schottky junction (Ni/DZIS) is fabricated and shows much better the photocatalytic hydrogen evolution rate without any noble metal cocatalysts. The improved photocatalytic performance is mainly attributed to the synergism of sulfur vacancy and Schottky junction accelerating the photogenerated charge transfer and thus inhibiting the charge recombination. [Display omitted] • Fabrication of Ni/ZnIn 2 S 4 nanosheet assembly with sulfur vacancy and Schottky junction (Ni/DZIS) through facile ethanediol-assisted solvothermal method. • The location of Ni at the hollow site of three S atoms next to sulfur vacancy on the ZnIn 2 S 4 (0 0 6) face. • The photocatalytic hydrogen evolution rate of Ni/DZIS up to 703 μmol g−1h−1 without any noble metal cocatalysts. Surface and interface engineering play vital roles on improving the photocatalytic hydrogen evolution. Herein, Ni/ZnIn 2 S 4 nanosheet assembly with sulfur vacancy and Schottky junction (Ni/DZIS) is fabricated through facile ethanediol-assisted solvothermal method. Density functional theory (DFT) calculation reveals that the Ni is absorbed at the hollow site of three S atoms next to sulfur vacancy on the ZnIn 2 S 4 (0 0 6) face due to the formation of sulfur vacancy. The resultant Ni/DZIS Schottky junction exhibits high photocatalytic H 2 evolution rate of 703 μmol g−1h−1 without any noble metal cocatalysts, which is 2.6 times higher than that of pristine ZnIn 2 S 4 nanosheets. The improved photocatalytic performance is mainly attributed to the synergism of sulfur vacancy and Schottky junction accelerating the photogenerated charge transfer and thus inhibiting the charge recombination. Moreover, the photocatalytic performance of Ni/DZIS nearly keeps constant even after six recycles, indicating the high stability and potential applications in field of energy. This work provides a convenient strategy for constructing efficient defective heterojunction assembly photocatalysts via surface and interface engineering. [ABSTRACT FROM AUTHOR]