Crystalline Carbon Nitride Research Articles

Metal Single Atom-Hydroxyl Incorporation in Poly(heptazine imide) to Create Active Sites for Photocatalytic Water Oxidation.

Poly(heptazine imide) (PHI) salts are extensively researched crystalline carbon nitride photocatalysts, but their photocatalytic water oxidation (PWO) performance is scarcely researched because of the difficulty in creating efficient active sites. Interference of metal ion (e.g., Na+ and K+) loss from the PHI salts in their PWO research has hardly been considered. Herein, metal single atom─OH (e.g., Co─OH) groups are incorporated into PHI to create efficient PWO active sites, via simple ion metathesis, hydrolysis, and deprotonation. The Co─OH modified PHI exhibits 9.3-fold higher PWO (oxygen evolution) activity than PHI, with an external quantum yield reaching 0.44% even at 600 nm. Excluding interference of the metal ion loss, the function of the Co─OH incorporation is evidenced mainly to facilitate the oxygen evolution reaction, as well as to promote photogenerated charge separation and raise visible light absorption, with the role of the OH especially revealed. Moreover, it is discovered that Na+ loss from sodium PHI will decrease its PWO activity, protonation of PHI has a detrimental effect on its PWO performance, and some other metal single atom─OH incorporation in PHI can also enhance its PWO activity. Overall, this work provides a general way to create PWO active sites in PHI.

Robust carbon nitride nanosheet interlayered thin-film nanocomposite membrane for enhanced organic solvent nanofiltration

The integration of a nanomaterial interlayer within a thin-film composite membrane can markedly enhance its performance in organic solvent nanofiltration (OSN). However, this enhancement often comes at the expense of membrane integrity due to differential swelling behaviors in diverse solvents. In this study, we present an interlayered thin film nanocomposite (TFNi) membrane that demonstrates both high permeance and robust stability, utilizing green, porous, and reactive crystalline carbon nitride (CCN) nanosheets as the functional interlayer. The results revealed that ascribed to the presence of the CCN interlayer, the membranes retained their rejection towards organic dyes even after 10 h of DMF exposure, while the organic solvent permeance was significantly improved by the DMF treatment. The methanol permeance of the CCN-TFNi-DMF membrane reached an impressive 8.77 L m−2 h−1 bar−1, sustaining stable performance throughout a 72 h test period under a pressure of 10 bar. We attributed this performance enhancement to the extra nanochannels introduced by the CCN nanosheets that bolstered the permeance of the TFNi membrane, as well as the formation of a stable polyamide film resulting from the reaction between the amino groups on the CCN nanosheet surface and trimesoyl chloride during the interfacial polymerization process. This work provides valuable insights into the development of structurally reinforced TFNi membranes with exceptional performance for OSN separation applications.

Preparation of high-efficient donor-π-acceptor system with crystalline g-C3N4 as charge transfer module for enhanced photocatalytic hydrogen evolution

Donor-π-acceptor (D-π-A) type photocatalysts with g-C3N4 as π-module have attracted much attention due to their optimized conjugate structure and enhanced electron directed driving. However, the inefficient charges migration of g-C3N4 due to its amorphous or semi-crystalline structure and limitation of available functional groups are present challenges. In this work, the D-π-A type high crystalline carbon nitride (HCCN) has been obtained by in-situ introducing amide and cyanide groups into the high-crystallinity melon framework. The synergistic effect of functional group modification and crystallinity regulation greatly enhances the electron induction driving and charge carrier density. Moreover, the density functional theory calculations demonstrate that the D-π-A structure could induce the local charge distribution of melon units to provide a unique and stable pathway for photoinduced charges migration. The as-prepared HCCN sample shows a superior visible-light photocatalytic performance for hydrogen evolution with an apparent quantum efficiency (AQE) of 12.2 ​% at 420 ​± ​15 ​nm, which is 23.7 times higher than that of original g-C3N4. Finally, the charge separation and transfer processes as well as the possible photocatalytic reaction mechanisms of HCCN sample are also investigated.

Suppressing Nonradiative Recombination through Dielectric Screening of Defects in Crystalline Carbon Nitride for Enhanced Photocatalytic Activity.

Abundant defect-induced nonradiative recombination greatly reduces the charge separation efficiency in photocatalysts. Dielectric screening of defects has been proven to be an effective strategy to improve the charge separation efficiency; however, it has been rarely reported in photocatalysis. Here, a developed calcium poly(heptazine imide) (CaPHI) is utilized as a model photocatalyst to explore the dielectric screening of defects. Through embedding potassium ions in CaPHI, the dipole moment and polarity of the PHI structure are increased, thus enhancing the dielectric constant and enabling the dielectric screening of defects. In addition, compared to the original CaPHI, the optimized Ca/KPHI exhibits a 79.3% reduction in defect capture cross-section, and a decrease in the nonradiative recombination rate from 0.6224 to 0.1452 ns-1, thus achieving an apparent quantum efficiency of 51.4% for H2 production at 420 nm. This proposed dielectric screening strategy effectively addresses the issue of slow carrier transport and separation caused by defect-induced nonradiative recombination in photocatalysts.

Gold nanoparticles decorated crystalline carbon nitride nano-walls as a SERS chip for rapid and sensitive detection of benzidine

Risk level of benzidine residue to the environment and food safety urges surface enhanced Raman scattering (SERS) substrates to develop with high sensitivity and rapid enrichment. Herein, a hybrid of Au NPs decorated crystalline carbon nitride nano-walls (Au/CCN NWs) is fabricated on Al sheet and employed as a SERS substrate for the first time. An electro-enhanced adsorption strategy is employed to endow as-prepared Au/CCN NWs/Al chip with rapid assay capability. Crystalline phase transition and nano-wall morphology respectively bestows high charge transfer efficiency and favorable enrichment activity upon Au/CCN NWs/Al chip, and the hybrid substrate owns a considerable enhancement factor of 1.76×106 under static adsorption mode. Moreover, Au/CCN NWs/Al substrate can achieve the saturation enrichment of benzidine in 120 s with the help of electro-enhanced adsorption, and gains a significantly enhanced signal response compared to static adsorption. Likewise, the highly sensitive response (1 μg L-1), superior reproducibility (RSD=9.11 %, n=100) and reliable accuracy (recovery rate of 95.55%-109.46%) jointly demonstrate that Au/CCN NWs/Al substrate may be applicable for detecting benzidine residue in actual application. This work offers an integrated solution to both enhance charge transfer efficiency and enrichment activity based on collaborative crystalline phase transition and electro-enhanced adsorption, and may inspire the design of novel noble metal/semiconductor hybrid SERS substrates.

Revealing the effect regularity of cations on electron storage capacity of poly(heptazine imide) in “dark photocatalysis”

As a crystalline carbon nitride material, poly(heptazine imide) (abbreviated as PHI) exhibits higher photoinduced charge separation performance than traditional melon-based carbon nitride. The excellent charge separation is mainly attributed to the fact that the photoinduced electrons can be captured by cations (such as K+ and H+) and further stored in the PHI framework with the presence of sacrificial agents (such as methanol). Due to this special property, the stored electrons can be used for delayed H2O2 or H2 production in the “dark photocatalysis” field. Nevertheless, the effect regularity of cations on the electron storage capacity of PHI is still not clear. In this work, this problem has been preliminarily revealed. The electron storage capacity of a series of PHI materials has been quantified by the H2O2 production test in dark conditions. The result indicates that the electron storage capacity of PHI samples shows a volcano curve with the alkali metal ion content. Based on experimental tests and theoretical simulations, it is concluded that the electron storage capacity of PHI is related to the conductivity of the cation and its binding force for photogenerated electrons.

Synergy of P doping and crystallinity modulation in carbon nitride for enhancing photocatalytic uranyl reduction

Doping modification is a useful way to promote the catalytic activity of carbon nitride (CN). However, most doped CNs have lower structural symmetry and several edge defects, which hinder the transfer of charge carriers. This work reports a P-doped crystalline carbon nitride (crystalline PCN) for the efficient photoreduction of uranyl. The thermal polymerization and salt post-treatment convert the amorphous PCN into crystalline PCN. Compared to the pristine CN, the crystalline PCN has over 1620 % higher activity for uranyl (U(VI)) reduction, reaching a 97.8 % reduction rate in 60 min. Furthermore, the 2-PCN shows excellent stability and a U(VI) removal efficiency >85.7 % in the pH range of 5–8. Characterization analysis reveal that both the P doping and crystalline modulation do not obviously change their morphology, light absorption property and energy band structure, but markedly promote the delocalization of electrons around the doped P atoms, thereby severely inhibit direct electron-hole recombination. Thus, the more efficient separation of charge carriers generates more reactive specials to participate in the photocatalytic uranyl reduction reaction. This study demonstrates a dual-modification strategy for the rational synthesis of highly active metal-free CN-based photocatalysts for uranyl reduction.

Surface nitrogen defect modified crystalline carbon nitride spheres with boosted carrier dynamics for efficient solar hydrogen production

Engineering of the defective structure and crystallinity of semiconductor photocatalysts to promote carrier dynamics has attracted considerable attention. This study presents the design of surface nitrogen defect modified crystalline carbon nitride spheres (QCN) with synergistically boosted surface and bulk carrier separation through a rapid thermal treatment coupled with a flux assisted strategy. Using supramolecular self-assembled polymer as the precursor, spherical crystalline CN heterojunctions are firstly prepared by a molten salt method to improve the separation of bulk carriers. Abundant nitrogen defects are then introduced onto the surface of crystalline CN through the following quick thermal treatment in air, which can generate a higher exciton density and drive rapid migration of surface carriers by acting as effective electron sinks. Furthermore, the defect level also improves the visible light utilization and provides more active centers for reactant adsorption and activation. As a result, QCN samples exhibit excellent performance in photocatalytic hydrogen evolution, with an optimal hydrogen production rate 4.3 times higher than that of pristine bulk CN under visible light irradiation. Moreover, the photocatalytic activities of QCN are dependent on the concentration of nitrogen defects, which can be flexibly adjusted via thermal treatment temperature. Such a two-step regulation strategy combining the distinctive advantages of surface defect structure and high crystallinity is beneficial for synergistic enhancement of photocatalytic performance, and provides new insights for sustainable energy production in the future.

Plasmonic Pt-PPCN/TiN Ohmic Junction for Photo-Thermo Catalytic Hydrogen Production.

The rational design of photocatalysts for improving the conversion of solar energy into hydrogen is a promising route for achieving carbon neutrality. Herein, we couple plasmonic titanium nitride (TiN) with highly crystalline potassium-doped polymeric carbon nitride (PPCN) to construct a PPCN/TiN ohmic junction. Such an ohmic junction not only broadens the absorption spectrum but also inhibits the recombination of electrons and holes. In addition, Pt nanoparticles are introduced into this ohmic junction to form plasmonic Pt-PPCN/TiN, improving the capture of hot electrons generated by TiN and thereby promoting the dissociation of the O-H bond in H2O. The energy barrier decreases from 0.7 to 0.2 eV. Enhanced separation of carrier, activation of water molecules, and capture of hot electrons are jointly promoting photo-thermo catalytic hydrogen production. Therefore, under full-spectrum irradiation, the hydrogen production rate of Pt-PPCN/TiN reaches 19 085 μmol g-1 h-1. This novel plasmonic photocatalyst is promising for full-spectrum photo-thermo catalytic hydrogen production.

Modification of crystalline graphitic carbon nitride for improve efficiency in photocatalytic destruction of volatile organic compounds (VOCs) under visible light irradiation

In this study, we show that the use of a mixture of melamine and oxalic acid during the synthesis of acid-treated crystalline graphitic carbon nitride samples significantly enhances its photocatalytic activity in VOCs destruction processes. The rate of photocatalytic ethanol destruction with the participation of modified crystalline graphitic carbon nitride obtained under optimal conditions is 67.1 μmol h−1, which is almost twice higher than sample synthesized in the absence of oxalic acid, and is two orders of magnitude higher than the activity of bulk g–C3N4. The synthesized materials were characterized using XRD, FT-IR, UV–Vis, PL, SEM, and EDXA methods. The high activity of the modified carbon nitride samples is attributed to increased light absorption in the visible region of the spectrum and better crystallinity, which can lead to more efficient separation and transport of photogenerated charges. To our knowledge, the effect of the simultaneous use of melamine and oxalic acid for obtaining acid-treated crystalline graphitic carbon nitride is, shown for the first time.

Microwave‐Assisted Confining Growth and Liquid Exfoliation of sp3‐Hybrid Carbon Nitride Nano/Micro‐Crystals

As one promising carbon‐based material, sp3‐hybrid carbon nitride has been predicted with various novel physicochemical properties. However, the synthesis of sp3‐hybrid carbon nitride is still limited by the nanaoscale, low crystallinity, complex source, and expensive instruments. Herein, we have presented a facile approach to the sp3‐hybrid carbon nitride nano/micro‐crystals with microwave‐assisted confining growth and liquid exfoliation. Actually, the carbon nitride nano/micro‐crystals can spontaneously emerge and grow in the microwave‐assisted polymerization of citric acid and urea, and the liquid exfoliation can break the bulk disorder polymer to retrieve the highly crystalline carbon nitride nano/micro‐crystals. The obtained carbon nitride nano/micro‐crystals present superior blue light absorption strength and surprising photoluminescence quantum yields of 57.96% in ethanol and 18.05% in solid state. The experimental characterizations and density functional theory calculations reveal that the interface‐trapped localized exciton may contribute to the excellent intrinsic light emission capability of carbon nitride nano/micro‐crystals and the interparticle staggered stacking will prevent the aggregation‐caused‐quenching partially. Finally, the carbon nitride nano/micro‐crystals are demonstrated to be potentially useful as the phosphor medium in light‐emitting‐diode for interrupting blue light‐induced eye damage. This work paves new light on the synthesis strategy of sp3‐hybrid carbon nitride materials and thus may push forward the development of multiple carbon nitride research.

Singlet oxygen species induced by colloidal crystalline carbon nitride induced for efficient H2O2 synthesis with in situ antibacterial effect

Solar-driven hydrogen (H2) and hydrogen peroxide (H2O2) generation over visible-light responsive carbon nitride (CN) photocatalysts for in situ efficient sterilization is a promising and eco-friendly strategy. Herein, a colloidal potassium-ion (K+) intercalated crystalline CN nanosheets (KCCN) photocatalyst was constructed for boosting synergetic H2O2 synthesis with isopropanol (IPA) oxidation and in situ antibacterial effect. The surface hydroxyl (−OH) and cyano (−CN) groups induced by molten salt (KCl)-assisted thermal treatments contributed to the colloidal nature of CN, facilitating for high wettability of KCCN in aqueous solution to gain active hydrogen (H+) from water sustainably. Meaningfully, the enhanced high-energy singlet oxygen species (1O2) produced by KCNN-2 were verified by electron paramagnetic resonance (EPR) and 9,10-anthracenediyl-bis(methylene)-dimalonic acid (ABDA)-fluorescent probe, significantly contributing to H2O2 production and antibacterial effect. Consequently, the optimal KCCN-2 exhibited a much enhanced H2 generation of 4.11 mmol g−1 h−1, and H2O2 production activity of 1.82 mmol L−1 h−1 with acetone yield rate of 47.3 mmol g−1 h−1 under visible-light (λ > 420 nm) irradiation in 10 vol% IPA solution. The in-situ generated H2O2 can be activated to produce reactive oxygen species (ROS), especially 1O2, to effectively kill the Escherichia coli, reaching an improved an antibacterial rate of 89.7% under stimulated sunlight irradiation in 1 h. This work could offer a new insight into the photoinduced ROS for aqueous H2O2 photosynthesis and antibacterial application.

Congener-welded crystalline carbon nitride membrane for robust and highly selective Li/Mg separation.

Extracting lithium from salt-lake brines critically relies on the separation of Li+ and Mg2+, which could combat the lithium shortage. However, designing robust sieving membrane with high Li+/Mg2+ selectivity in the long-time operation has remained highly challenging. Here, we demonstrate a bioinspired congener-welded crystalline carbon nitride membrane that can accomplish efficient and stable monovalent ion sieving over divalent Mg ion. The crystalline carbon nitrides have uniform and narrow pore size to reject the large hydrated Mg2+ and rich ligating sites to facilitate an almost barrierless Li+ transport as suggested by ab initio simulations. These crystals were then welded by vapor-deposited congeners, i.e., amorphous polymer carbon nitride, which have similar composition and chemistry with the crystals, forming intimate and compatible crystal/polymer interface. As a result, our membrane can sieve out highly dilute Li+ (0.002 M) from concentrated Mg2+ (1.0 M) with a high selectivity of 1708, and can be continuously operated for 10 days.

Crystallinity modulation and microenvironment engineering synergistically manipulate ROS generation on Ni single-atom photocatalysts

The microenvironment modulation of metal-based catalysis sites plays a critical role in single-atom photocatalysis, and remains a grand challenge yet. Herein, the single-atom Ni anchored crystalline carbon nitride (Ni/CCN) nanowire arrays are reported. The obtained Ni/CCN nanowire arrays exhibit an impressive photocatalytic activity (>96% degradation of pharmaceuticals and personal care products (PPCPs) in only 5 min) and photocatalytic rate (maximum 0.5941 min−1) with only clean solar energy input. The Ni/CCN catalyst attached on microfiltration membrane in the continuous flow experiments exhibits >90% PPCPs degradation efficiency over 10 h, demonstrating the ultrahigh activity and long-term operation of the Ni/CCN catalysts. The results of electron spin resonance analysis, probe experiment and theoretical calculations demonstrate that the promoted generation of reactive oxygen species (ROS) highly relies on the crystallinity regulation and microenvironment engineering of active metal sites, which are consequently utilized to trigger the rapid degradation of PPCPs. The introduced Ni-N4 moiety disrupts the uniform distribution of delocalized electrons and precisely tunes the electronic distribution of the microenvironment in CCN, providing an electron-rich region coupled with strong electron transfer effect between Ni and adsorbed O, thus optimizing the crucial step for molecular oxygen activation. This work offers a new idea of photocatalysis from theoretical design towards broad applications through the perspective about modulating microenvironment of active metal sites and optimizing intrinsic electronic properties.

Effect of hydrogen sources toward the CO2 photoreduction on boron decorated crystalline carbon nitride

Photocatalytic CO2 conversion to industrial fuels is considered an effective measure to solve energy and environmental problems. Presently, Catalysts for CO2 reduction reaction (CO2RR) are mostly confined to metal-based materials, but non-metal materials are less explored. We decorate the highly crystalline carbon nitride, i.e., poly(triazine) imides (PTI), with non-metallic boron (B) to obtain two B/PTI catalysts: Bi/PTI with B being deposited into the six-fold cavity of the PTI, and Bs/PTI with B substituting for C in PTI. For CO2RR, Bi/PTI follows a quasi Mars-van Krevelen process, but the high exposure of Bi results in an overly strong interaction with intermediates, inhibiting the reactivity. In contrast, Bs/PTI enhances the binding with intermediates by introducing Lewis acid-base pairs (B-N), which reduce the ring conjugation effect and induce the enrichment of electrons at the pyridine N. Hence, CO2 reduction with the adsorbed H* (Ha) hydrogenation mechanism in Bs/PTI has a significant reactivity.

Diastereoselective dearomatization of indoles via photocatalytic hydroboration on hydramine-functionalized carbon nitride.

A protocol for trans-hydroboration of indole derivatives using heterogeneous photocatalysis with NHC-borane has been developed, addressing a persistent challenge in organic synthesis. The protocol, leveraging high crystalline vacancy-engineered polymeric carbon nitride as a catalyst, enables diastereoselective synthesis, expanding substrate scope and complementing existing methods. The approach emphasizes eco-friendliness, cost-effectiveness, and scalability, making it suitable for industrial applications, particularly in renewable energy contexts. The catalyst's superior performance, attributed to its rich carbon-vacancies and well-ordered structure, surpasses more expensive homogeneous alternatives, enhancing viability for large-scale use. This innovation holds promise for synthesizing bioactive compounds and materials relevant to medicinal chemistry and beyond.

Chloride Ion-Induced Spatial Separation and Long Recombination Time of Photogenerated Electrons and Holes in Crystalline Carbon Nitride.

Poly(triazine imide)·Li+Cl- (PTI/Li+Cl-) as one of the most reported crystalline carbon nitrides has shown exciting potential for photocatalysis. However, understanding the role of Li+/Cl- in the photoexcited charge transfer in the time and space of PTI is a challenging problem. Here, we have investigated the nonradiative charge recombination of series ion intercalated PTI systems (PTI/Li+X-, where X = F, Cl, Br, and I) by performing the ab initio nonadiabatic molecular dynamics simulations. The results indicate that the intercalated anions in PTI/Li+Cl- and PTI/Li+Br- have the potential to trap holes, separate the electrons and holes, and prolong the nonradiative electron-hole recombination. In particular, ∼70% of holes in PTI/Li+Cl- can transport among interlayers toward the {0001} planes, while most of the electrons are transferred to the {101̅0} planes, exhibiting different transport pathways and directions. Furthermore, PTI/Li+Cl- has an electron-hole recombination time as long as 136 ns, which explains its excellent optoelectronic properties. This work provides a theoretical baseline for the reported facet engineering improvement of crystalline carbon nitride for overall water splitting.

Harnessing the Power of Light: The Synergistic Effects of Crystalline Carbon Nitride and Ti3C2Tx MXene in Photocatalytic Hydrogen Production.

Photocatalytic hydrogen evolution is an environmentally friendly means of energy generation. Although g-C3N4 possesses fascinating features, its inherent shortcomings limit its photocatalytic applications. Therefore, modifying the intrinsic properties of g-C3N4 and introducing cocatalysts are essential to ameliorate the photocatalytic efficiency. To achieve this, metal-like Ti3C2Tx is integrated with crystalline g-C3N4 via a combined salt-assisted and freeze-drying approach to form crystalline g-C3N4/Ti3C2Tx (CCN/TCT) hybrids with different Ti3C2Tx loading amounts (0, 0.2, 0.3, 0.4, 0.5, 1, 5, 10 wt.%). Benefiting from the crystallization of CN, as evidenced by the XRD graph, and the marvelous conductivity of Ti3C2Tx supported by EIS plots, CCN/TCT/Pt loaded with 0.5 wt.% Ti3C2Tx displays an elevated H2 (2) should be subscripted evolution rate of 2651.93µmol g-1 h-1 and a high apparent quantum efficiency of 7.26% (420nm), outperforming CN/Pt, CCN/Pt, and other CCN/TCT/Pt hybrids. The enhanced performance is attributed to the synergistic effect of the highly crystalline structure of CCN that enables fleet charge transport and the efficient dual cocatalysts, Ti3C2Tx and Pt, that foster charge separation and provide plentiful active sites. This work demonstrates the potential of CCN/TCT as a promising material for hydrogen production, suggesting a significant advancement in the design of CCN heterostructures for effective photocatalytic systems.

Surface cyano groups optimize the charge transfer of poly heptazine imide for enhanced photocatalytic H2 evolution

Surface functionalization has been considered as an effective strategy to manipulate charge separation of carbon nitride and therefore to largely improve the photocatalytic H2 evolution efficiency. Poly heptazine imide (PHI) is a new class of crystalline carbon nitride frameworks that exhibits remarkable photocatalytic performance for hydrogen evolution. To further improve the H2 evolution performance of PHI and explore the reaction mechanism, ammonium thiocyanate was used as a precursor for the synthesis of poly heptazine imide at elevated temperatures under molten salt conditions. The optimized PHI with an abundance of surface cyano groups shows a significantly enhanced photocatalytic performance for H2 evolution, which is 4.3 times that on pristine PCN. Most importantly, the surface cyano group adjusts the electron intensity of the polymeric framework, enhances the light absorbance, reduces the bandgap, and improves the charge separation efficiency. The synthetic technique also could be applied to other sulfur-containing precursors for the synthesis of PHI frameworks with excellent hydrogen evolution production performance.

Singlet Oxygen Formation Mechanism for the H2O2-Based Fenton-like Reaction Catalyzed by the Carbon Nitride Homojunction.

The singlet oxygen (1O2) oxidation process activated by metal-free catalysts has recently attracted considerable attention for organic pollutant degradation; however, the 1O2 formation remains controversial. Simultaneously, the catalytic activity of the metal-free catalyst limits the practical application. In this study, carbon nitride (HCCN) containing an intramolecular homojunction, a kind of metal-free catalyst, exhibits excellent activity compared to g-C3N4 (CN) and crystalline carbon nitride (HCN) for tetracycline hydrochloride degradation through the H2O2-based Fenton-like reaction. The rate constant for HCCN increased about 16.1 and 8.9 times than that of CN and HCN, respectively. The activity of HCCN was enhanced, and the dominant reactive oxygen species (ROS) changed from hydroxyl radicals (•OH) to 1O2 with an increase in pH from 4.5 to 11.5. A novel formation pathway of 1O2 was revealed. This result is different from the normal reference, in which •OH is always the primary ROS in the H2O2-based Fenton-like reaction. This study may provide a possible strategy for the investigation on the nonradical oxidation process in the Fenton-like reaction.