Shear Stress Triggers Ultrathin-Nanosheet Carbon Nitride Assembly for Photocatalytic H2O2 Production Coupled with Selective Alcohol Oxidation

Constructing homo/hetero-nuclear carbon and oxygen atoms co-doped graphitic carbon nitride assisted by ionic liquid for photothermal synergistic catalytic oxidation of cyclohexane

The adoption of photothermal synergistic catalysis for cyclohexane oxidation can balance the advantages of high conversion of thermal catalysis and high selectivity of photocatalytic technology to achieve better catalytic performance. Here, we prepared functional carbon nitride (BCA-CN) by self-assembly strategy of ionic liquid [Bmim]CA (1-Butyl-3-methylimidazole citrate) with melamine and cyanuric acid utilizing abundant elements and anionic/cationic hydrogen bonding interactions. The introduction of [Bmim]CA embeds C-C (carbon and carbon band) and C-O-C (ether bond) structures into graphitic carbon nitride (g-C3N4) framework, significantly improving light absorption capacity and migration of photo generated charge carriers. Compared to g-C3N4, both BCA-CN increases cyclohexane conversion and KA oil (the mixture of cyclohexanol and cyclohexanone) selectivity by 1.3 times under photothermal catalysis. The surface reactions are facilitated by changing adsorption sites of cyclohexane to increase adsorption energy and obtaining more hydroxyl radicals and superoxide radicals. Furthermore, the enhanced selectivity is attributed to the difficulty in generating cyclohexanone radicals. This work offers the reference scheme for the development of efficient photothermal catalysts in the selective oxidation of cyclohexane.

Metal-Semiconductor Heterojunction with Ohmic Contact Realizes Efficient Infrared-Light-Driven Photocatalysis

Efficient utilization of solar energy for photocatalytic applications, particularly in the infrared spectrum, is crucial for addressing environmental challenges and energy scarcity. Herein we present a general strategy for constructing efficient infrared-driven photocatalysts in a metal/semiconductor heterojunction with Ohmic contact, where metals with low work function as the infrared-light absorber and semiconductors with electron storage ability can overcome the unfavorable electron flowback. Taking the NixB/MO2 (M = Ce, Ti, Sn, Ge, Zr, etc.) heterojunction as an example, both experimental and theoretical investigations reveal that the formation of an Ohmic contact facilitates the transfer of hot electrons from NixB to MO2, which are stored by the ion redox pairs for the variable valence character of M. As expected, the heterojunction exhibits remarkable photocatalytic activity under infrared light (λ ≥ 800 nm), as evidenced by the efficient photofixation of CO2 to high-value-added cyclic carbonates. This study offers a general platform for designing infrared-light-driven photocatalysts.

Introducing Br, K, and cyano group into carbon nitride for efficient photocatalytic hydrogen peroxide production then in situ tetracycline mineralization

In this work, Br, K-doped and cyano group-rich carbon nitride (CN) were prepared via pyrolysis of molten urea and 6-Bromopyridine-3-carbaldehyde, followed by re-calcination with potassium thiocyanate. The hydrogen peroxide (H2O2) evolution and in situ tetracycline (TC) mineralization performances of the prepared samples were studied. The optimal sample could produce 9127 μmol g-1 h-1 H2O2 from 10 vol% ethanol solution and air atmosphere, which was 10.9 times higher than that of pristine CN. With addition of 4 mg L-1 Fe2+ ions, 97.2% of TC (10 mg L-1) and 98.7% of total organic carbon were removed in 30 min under the actions of holes, hydroxyl and superoxide radicals. The high H2O2 yield and TC mineralization ratio were attributed to the increased light absorption, efficient electrons-holes separation, enhanced surface O2 adsorption (0.3878 mmol g-1), and accelerated conversion from Fe3+ to Fe2+ ions. Meanwhile, the system possessed good reusability in H2O2 evolution and TC removal. It is expected that this work can provide new ideas to design CN-based photo-Fenton system to treat wastewater.

Assembling carbon nitride quantum dots into hollow fusiformis and loading CoP for photocatalytic hydrogen evolution

The self-assembled carbon nitride quantum dots (CNQDs) has been largely advanced owing to the structure-relative photocatalytic activities, especially its electronic structure, which can be regulated by defects, functional groups, and doping. However, there are still issues such as wide band gaps for the assembles and severe recombination of photoinduced charges. Herein, we demonstrate the self-assembly of CNQDs into fusiform hollow superstructures (CNFHs), induced by hydrogen bonding between the terminal functional groups (-OH, -COOH, and -NH2). During the top-down assembly process, the hydrogen bonding dominates and initiates lateral cross-linking between adjacent CNQDs, which further twist into fusiform hollow structures. Benefitted greatly from the ultrathin and hollow nature of the superstructure that provides more exposed active sites, coupled with the introduction of phosphorus doping atoms into the framework induced narrowed band gap, CNFHs exhibits an 18-fold higher activity than the bulk counterpart toward photocatalytic hydrogen evolution after loading the CoP co-catalyst. This work presents a new platform to design and manipulate carbon nitride superstructures.

H2O2 Photosynthesis from H2O and O2 under Weak Light by Carbon Nitrides with the Piezoelectric Effect

Driven by the essential need of a green, safe, and low-cost approach to producing H2O2, a highly valuable multifunctional chemical, artificial photosynthesis emerges as a promising avenue. However, current catalyst systems remain challenging, due to the need of high-density sunlight, poor selectivity and activity, or/and unfavorable thermodynamics. Here, we reported that an indirect 2e- water oxidation reaction (WOR) in photocatalytic H2O2 production was unusually activated by C5N2 with piezoelectric effects. Interestingly, under ultrasonication, C5N2 exhibited an overall H2O2 photosynthesis rate of 918.4 μM/h and an exceptionally high solar-to-chemical conversion efficiency of 2.6% after calibration under weak light (0.1 sun). Mechanism studies showed that the piezoelectric effect of carbon nitride overcame the high uphill thermodynamics of *OH intermediate generation, which enabled a new pathway for 2e- WOR, the kinetic limiting step in the overall H2O2 production from H2O and O2. Benefiting from the outstanding sonication-assisted photocatalytic H2O2 generation under weak light, the concept was further successfully adapted to biomedical applications in efficient sono-photochemodynamic therapy for cancer treatment and water purification.

Tuning electronic structure of metal-free dual-site catalyst enables exclusive singlet oxygen production and in-situ utilization

Developing eco-friendly catalysts for effective water purification with minimal oxidant use is imperative. Herein, we present a metal-free and nitrogen/fluorine dual-site catalyst, enhancing the selectivity and utilization of singlet oxygen (1O2) for water decontamination. Advanced theoretical simulations reveal that synergistic fluorine-nitrogen interactions modulate electron distribution and polarization, creating asymmetric surface electron configurations and electron-deficient nitrogen vacancies. These properties trigger the selective generation of 1O2 from peroxymonosulfate (PMS) and improve the utilization of neighboring reactive oxygen species, facilitated by contaminant enrichment at the fluorine-carbon Lewis-acid adsorption sites. Utilizing these insights, we synthesize the catalyst through montmorillonite (MMT)-assisted pyrolysis (NFC/M). This method leverages the role of MMT as an in-situ layer-stacked template, enabling controlled decomposition of carbon, nitrogen, and fluorine precursors and resulting in a catalyst with enhanced structural adaptability, reactive site accessibility, and mass-transfer capacity. The NFC/M demonstrates an impressive 290.5-fold increase in phenol degradation efficiency than the single-site analogs, outperforming most of metal-based catalysts. This work not only underscores the potential of precise electronic and structural manipulations in catalyst design but also advances the development of efficient and sustainable solutions for water purification.

Tandem Proton Transfer in Carboxylated Supramolecular Polymer for Highly Efficient Overall Photosynthesis of Hydrogen Peroxide

Proton supply is as critical as O2 activation for artificial photosynthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction reaction (2e- ORR). However, proton release via water dissociation is frequently hindered because of the sluggish water oxidation reaction (WOR), extremely limiting the efficiency of photocatalytic H2O2 production. To tackle this challenge, carboxyl-enriched supramolecular polymer (perylene tetracarboxylic acid-PTCA) is elaborately prepared by molecular self-assembly for overall photosynthesis of H2O2. Interestingly, the interconversion between carboxyl as Brønsted acid and its conjugated base realizes rapid proton circulation. Through this efficient tandem proton transfer process, the spatial effect of photocatalytic reduction and oxidation reaction is greatly enhanced with reduced reaction barrier. This significantly facilitates 2e- photocatalytic ORR to synthesize H2O2 and in the meanwhile promotes 4e- photocatalytic WOR to evolve O2. Consequently, the as-developed PTCA exhibits a remarkable H2O2 yield of 185.6 μM h-1 in pure water and air atmosphere under visible light illumination. More impressively, an appreciable H2O2 yield of 78.6 μM h-1 can be well maintained in an anaerobic system owing to in situ O2 generation by 4e- photocatalytic WOR. Our study presents a novel concept for artificial photosynthesis of H2O2 via constructing efficient proton transfer pathway to enable rapid proton circulation.

Creation of Interfacial S4-Sn-N2 Electron Pathways for Efficient Light-Driven Hydrogen Evolution

Establishing effective charge transfer channels between two semiconductors is key to improving photocatalytic activity. However, controlling hetero-structures in situ and designing binding modes pose significant challenges. Herein, hydrolytic SnCl2·2H2O is selected as the metal source and loaded in situ onto a layered carbon nitriden supramolecular precursor. A composite photocatalyst, S4-Sn-N2, with electron pathways of SnS2 and tubular carbon nitriden (TCN) is prepared through pyrolysis and vulcanization processes. The contact interface of SnS2-TCN is increased significantly, promoting the formation of S4-Sn-N2 micro-structure in a Z-scheme charge transfer channel. This structure accelerates the separation and transport of photogenerated carriers, maintains the stronger redox ability, and improves the stability of SnS2 in this series of heterojunctions. Therefore, the catalyst demonstrated exceptional photocatalytic hydrogen production efficiency, achieving a reaction rate of 86.4 µmol h-1, which is 3.15 times greater than that of bare TCN.

Photochromic radical states in 3D covalent organic frameworks with zyg topology for enhanced photocatalysis

Covalent-organic frameworks (COFs) with photoinduced donor-acceptor (D-A) radical pairs show enhanced photocatalytic activity in principle. However, achieving long-lived charge separation in COFs proves challenging due to the rapid charge recombination. Here, we develop a novel strategy by combining [6 + 4] nodes to construct zyg-type 3D COFs, first reported in COF chemistry. This structure type exhibits a fused Olympic-rings-like shape, which provides a platform for stabilizing the photoinduced D-A radical pairs. The zyg-type COFs containing catalytically active moieties such as triphenylamine and phenothiazine (PTZ) show superior photocatalytic production rates of hydrogen peroxide (H2O2). Significantly, the photochromic radical states of these COFs show up to 400% enhancement in photocatalytic activity compared to the parent states, achieving a remarkable H2O2 synthesis rate of 3324 μmol g-1 h-1, which makes the PTZ-COF one of the best crystalline porous photocatalysts in H2O2 production. This work will shed light on the synthesis of efficient 3D COF photocatalysts built on topologies that can facilitate photogenerating D-A radical pairs for enhanced photocatalysis.

Hierarchical organic microspheres from diverse molecular building blocks

Microspherical structures find broad application in chemistry and materials science, including in separations and purifications, energy storage and conversion, organic and biocatalysis, and as artificial and bioactive scaffolds. Despite this utility, the systematic diversification of their morphology and function remains hindered by the limited range of their molecular building blocks. Drawing upon the design principles of reticular synthesis, where diverse organic molecules generate varied porous frameworks, we show herein how analogous microspherical structures can be generated under mild conditions. The assembly of simple organic molecules into microspherical structures with advanced morphologies represents a grand challenge. Beginning with a partially condensed Schiff base which self-assembles into a hierarchical organic microsphere, we systematically synthesized sixteen microspheres from diverse molecular building blocks. We subsequently explicate the mechanism of hierarchical assembly through which these hierarchical organic microspheres are produced, isolating the initial monomer, intermediate substructures, and eventual microspheres. Furthermore, the open cavities present on the surfaces of these constructs provided distinctive adsorptive properties, which we harnessed for the immobilization of enzymes and bacteriophages. Holistically, these hierarchical organic microspheres provide an approach for designing multi-functional superstructures with advanced morphologies derived from simple organic molecules, revealing an extended length scale for reticular synthesis.

Construction of Fe(III) Active Sites on Phenanthroline-Grafted g-C3N4: Reduced Work Function and Enhanced Intramolecular Charge Transfer for Efficient N2 Photofixation

Photocatalytic nitrogen fixation is one of the important pathways for green and sustainable ammonia synthesis, but the extremely high bonding energy of the N≡N triple bond makes it difficult for conventional nitrogen fixation photocatalysts to directly activate and hydrogenate. Given this, we covalently grafted the phenanthroline unit onto graphitic carbon nitride nanosheets (CN) by the simple thermal oxidation method and complexed it with transition metal Fe3+ ions to obtain stable dispersed Fe active sites, which can significantly improve the photocatalytic activity. The Fe(III)-4-P-CN photocatalyst morphology consists of porous lamellar structures internally connected by nanowires. The special morphology of the catalysts gives them excellent nitrogen fixation performance, with an average NH3 yield of 492.9 μmol g-1 h-1, which is 6.5 times higher than that of the pristine CN, as well as better photocatalytic cycling stability. Comprehensive experiments and density-functional theory results show that Fe(III)-4-P-CN is more favorable than pristine CN for *N2 activation, effectively lowering the reaction energy barrier. Moreover, other byproducts (such as nitrate and H2O2) are also produced during the photocatalytic nitrogen fixation process, which also provides a new way for nitrogen-fixing photocatalysts to achieve multifunctional applications.

Self-Powered Immunoassay of Norovirus in Human Stools by π-Electron-Rich Homojunction for Enhanced Charge Transfer

Norovirus (NoV) stands as a significant causative agent of nonbacterial acute gastroenteritis on a global scale, presenting a substantial threat to public health. Hence, the development of simple and rapid analytical techniques for NoV detection holds great importance in preventing and controlling the outbreak of the epidemic. In this work, a self-powered photoelectrochemical (PEC) immunosensor of NoV capsid protein (VP1) was proposed by the π-electron-rich carbon nitride homojunction (ER-CNH) as the photoanode. C4N2 ring derived from π-rich locust bean gum was introduced into the tri-s-triazine structure, creating a large π-delocalized conjugated carbon nitride homojunction. This strategy enhances the C/N atomic ratio, which widens light utilization, narrows the bandgap, and optimizes the electronic band structure of carbon nitride. By introduction of a π-rich conjugated structure, p-type domains were induced within n-type domains to build the internal electric field at the interface, thus forming a p-n homojunction to boost carrier separation and transfer. The ER-CNH photoanode exhibited excellent photoelectric performance and water oxidation capacity. Since VP1 inhibits the water oxidation of the ER-CNH photoanode, the open-circuit potential of the as-prepared PEC immunosensor system was reduced for detecting NoV VP1. The self-powered PEC immunosensor achieved a remarkably low detection limit (∼5 fg mL-1) and displayed high stability and applicability for actual stool samples. This research serves as a foundation concept for constructing immunosensors to detect other viruses and promotes the application of self-powered systems for life safety.

Recent developments in photocatalytic production of hydrogen peroxide

Hydrogen peroxide (H2O2), an environmentally friendly strong oxidant and energy carrier, has attracted widespread attention in photocatalysis. Artificial photosynthesis of H2O2 using water and oxygen as raw materials, solar energy as an energy source, and semiconductor materials as catalysts is considered a promising technology. In the past few decades, encouraging progress has been made in the photocatalytic production of H2O2. Therefore, we summarize the research achievements in this field in recent years. This review first briefly introduces the reaction pathway, detection techniques and evaluation metrics. Then, the recent advances in photocatalysts are highlighted. Furthermore, the existing challenges and possible solutions in this field are presented. At last, we look forward to the future development direction of this field. This review provides valuable insights and guidance for efficient photocatalytic H2O2 production.

Unravelling the Photoelectrochemical Water Splitting of Nanometer-Thick Carbon Nitride Layer

Matching the thickness of the graphitic carbon nitride (CN) nanolayer with the charge diffusion length is expected to compensate for the poor intrinsic conductivity and charge recombination in CN for photoelectrochemical cells (PEC). Herein, the compact CN nanolayer with tunable thickness is in situ coated on carbon fibers. The compact packing along with good contact with the substrate improves the electron transport and alleviates the charge recombination. The PEC investigation shows CN nanolayer of 93 nm-thick yields an optimum photocurrent of 116 µA cm-2 at 1.23 V versus RHE, comparable to most micrometer-thick CN layers, with a low onset potential of 0.2 V in 1 m KOH under 1 sun illumination. This optimum performance suggests the electron diffusion length matches with the thickness of the CN nanolayer. Further deposition of NiFe-layered double hydroxide enhanced the surface water oxidation kinetics, delivering an improved photocurrent of 210 µA cm-2 with IPCE of 12.8% at 400 nm. The CN nanolayer also shows extended potential in PEC organic synthesis. This work experimentally reveals the PEC behavior of the nanometer-thick CN layer, providing new insights into CN in the application of energy and environment-related fields.

Carbon Dots Anchoring Single-Atom Pt on C3N4 Boosting Photocatalytic Hydrogen Evolution

Carbon nitride (C3N4) has gained considerable attention and has been regarded as an ideal candidate for photocatalytic hydrogen evolution. However, its photocatalytic efficiency is still unsatisfactory due to the rapid recombination rate of photo-generated carriers and restricted surface area with few active sites. Herein, we successfully synthesized a single-atom Pt cocatalyst-loaded photocatalyst by utilizing the anchoring effect of carbon dots (CDs) on C3N4. The introduction of CDs onto the porous C3N4 matrix can greatly enhance the specific surface area of C3N4 to provide more surface-active sites, increase light absorption capabilities, as well as improve the charge separation efficiency. Notably, the functional groups of CDs can efficiently anchor the single-atom Pt, thus improving the atomic utilization efficiency of Pt cocatalysts. A strong interaction is formed via the connection of Pt-N bonds, which enhances the efficiency of photogenerated electron separation. This unique structure remarkably improves its H2 evolution performance under visible light irradiation with a rate of 15.09 mmol h-1 g-1. This work provides a new approach to constructing efficient photocatalysts by using CDs for sustainable hydrogen generation, offering a practical approach to utilizing solar energy for clean fuel production.

Weak-Field Electro-Flash Induced Asymmetric Catalytic Sites toward Efficient Solar Hydrogen Peroxide Production

Borocarbonitride (BCN), in a mesoscopic asymmetric state, is regarded as a promising photocatalyst for artificial photosynthesis. However, BCN materials reported in the literature primarily consist of symmetric N-[B]3 units, which generate highly spatial coupled electron-hole pairs upon irradiation, thus kinetically suppressing the solar-to-chemical conversion efficiency. Here, we propose a facile and fast weak-field electro-flash strategy, with which structural symmetry breaking is introduced on key nitrogen sites. As-obtained double-substituted BCN (ds-BCN) possesses high-concentration asymmetric [B]2-N-C coordination, which displays a highly separated electron-hole state and broad visible-light harvesting, as well as provides electron-rich N sites for O2 affinity. Thereby, ds-BCN delivers an apparent quantum yield of 7.6% at 400 nm and a solar-to-chemical conversion efficiency of 0.3% for selective 2e-reduction of O2 to H2O2, over 4-fold higher than that of the traditional calcined BCN analogue and superior to the metal-free C3N4-based photocatalysts reported so far. The weak-field electro-flash method and as-induced catalytic site symmetry-breaking methodologically provide a new method for the fast and low-cost fabrication of efficient nonmetallic catalysts toward solar-to-chemical conversions.

Controlled synthesis of 2D-2D conductive metal-organic framework/g-C3N4 heterojunctions for efficient photocatalytic hydrogen evolution

Designing photocatalysts with efficient charge separation and electron transport capabilities to achieve efficient visible-driven hydrogen production remains a challenge. Herein, 2D-2D conductive metal-organic framework/g-C3N4 heterojunctions were successfully prepared by an in situ assembly. Compared to pristine g-C3N4, the ratio-optimized Ni-CAT-1/g-C3N4 exhibits approximately 3.6 times higher visible-light H2 production activity, reaching 14 mmol g-1. Through investigations using time-resolved photoluminescence, surface photovoltage, and wavelength-dependent photocurrent action spectroscopies, it is determined that the improved photocatalytic performance is attributed to enhanced charge transfer and separation, specifically the efficient transfer of excited high-energy-level electrons from g-C3N4 to Ni-CAT in the heterojunctions. Furthermore, the high electrical conductivity of Ni-CAT enables rapid electron transport, contributing to the overall enhanced performance. This work provides a feasible strategy to construct efficient dimension-matched g-C3N4-based heterojunction photocatalysts with high-efficiency charge separation for solar-driven H2 production.

A green and environmentally benign route to synthesizing Z-scheme Bi2S3-TCN photocatalyst for efficient hydrogen production

Designing and developing photocatalysts with excellent performance in order to achieve efficient hydrogen production is an important strategy for addressing future energy and environmental challenges. Traditional single-phase photocatalytic materials either have a large bandgap and low visible light response or experience rapid recombination of the photogenerated carriers with low quantum efficiency, seriously hindering their photocatalytic applications. To solve these issues, an important solution is to construct well-matched heterojunctions with highly efficient charge separation capabilities. To this end, an in situ sulfurization reaction was adopted after the deposition of Bi3+ supramolecular complex on a layered supramolecular precursor of tubular carbon nitride (TCN). X-ray diffraction (XRD) patterns confirmed that the as-prepared sample has a good crystalline structure without any other impurities, while high-resolution transmission electron microscopy (HR-TEM) revealed that the heterojunction possesses a 2D structure with a layer of nano-array on its surface. Combined Fourier-transform infrared (FT-IR) spectra and energy-dispersive X-ray spectroscopy (EDX) revealed the interfacial interactions. Owing to the formation of the Z-scheme heterojunction, the visible light adsorption and the separation efficiency of the photo-generated carriers are both obviously enhanced, leaving the high energy electrons and high oxidative holes to participate in the photocatalytic reactions. As a result, the photocatalytic hydrogen evolution rate of Bi2S3-TCN achieves 65.2 μmol g-1·h-1. This proposed green and environmentally benign route can also be applied to construct other sulfides with 2D TCN, providing some important information for the design and optimization of novel carbon-nitride-based semiconductors.

Halogen-Modulated 2D Coordination Polymers for Efficient Hydrogen Peroxide Photosynthesis under Air and Pure Water Conditions

H2 O2 is a widely used eco-friendly oxidant and a potential energy carrier. Photocatalytic H2 O2 production from water and O2 is an ideal approach with the potential to address the current energy crisis and environmental issues. Three zig-zag two-dimensional coordination polymers (2D CPs), named CuX-dptz, were synthesized by a rapid and facile method at room temperature, showing preeminent H2 O2 photoproduction performance under pure water and open air without any additives. CuBr-dptz exhibits a H2 O2 production rate high up to 1874 μmol g-1  h-1 , exceeding most reported photocatalysts under this condition, even comparable to those supported by sacrificial agents and O2 . The coordination environment of Cu can be modulated by halogen atoms (X=Cl, Br, I), which in turn affects the electron transfer process and finally determines the reaction activity. This is the first time that 2D CPs have been used for photocatalytic H2 O2 production in such challenging conditions, which provides a new pathway for the development of portable in situ H2 O2 photosynthesis devices.

Pauling-Type Adsorption of O2 Induced by Heteroatom Doped ZnIn2 S4 for Boosted Solar-Driven H2 O2 Production

Breaking the trade-off between activity and selectivity has perennially been a formidable endeavor in the field of hydrogen peroxide (H2 O2 ) photosynthesis, especially the side-on configuration of oxygen (O2 ) on the catalyst surface will cause the cleavage of O-O bonds, which drastically hinders the H2 O2 production performance. Herein, we present an atomically heteroatom P doped ZnIn2 S4 catalyst with tunable oxygen adsorption configuration to accelerate the ORR kinetics essential for solar-driven H2 O2 production. Indeed, the spectroscopy characterizations (such as EXAFS and in situ FTIR) and DFT calculations reveal that heteroatom P doped ZnIn2 S4 at substitutional and interstitial sites, which not only optimizes the coordination environment of Zn active sites, but also facilitates electron transfer to the Zn sites and improves charge density, avoiding the breakage of O-O bonds and reducing the energy barriers to H2 O2 production. As a result, the oxygen adsorption configuration is regulated from side-on (Yeager-type) to end-on (Pauling-type), resulting in the accelerated ORR kinetics from 874.94 to 2107.66 μmol g-1  h-1 . This finding offers a new avenue toward strategic tailoring oxygen adsorption configuration by the rational design of doped photocatalyst.