Catalytic Active Sites Research Articles

Efficient lignin hydrogenolysis over N-doped macroporous carbon supported Ru catalyst

To cope with the challenge of insufficient interaction between lignin macromolecules and catalytic active sites in heterocatalysis systems which hindered the efficient hydrogenolysis of lignin, a lignin-derived N-doped macroporous carbon supported Ru catalyst (Ru/LNPC) was prepared via the pyrolysis of alkali lignin with potassium hydroxide as the activator and ammonium oxalate as the pore forming agent. The LNPC carrier featured a hierarchical porous structure with the diameter of macropores ranging from 50 nm to 10 μm, enhancing the adequately contact between the lignin macromolecules and Ru NPs. The doping nitrogen in the carbon carrier led to well dispersed Ru nanoparticles with average size of 1.08 nm, providing abundant active metallic centers. Therefore, Ru/LNPC exhibited excellent catalytic activity and stability to hydrogenolysis of lignin. Under the condition of 1.0 MPa H2 at 280 ºC for 2 h, Ru/LNPC contributed to the yield of 45.6 % aromatic monomers from the depolymerization of lignin. After five recycling, Ru/LNPC still showed significant activity. This work provided a new strategy for designing catalysts for efficient hydrogenolysis of lignin and further facilitating its high-value utilization.

Turning Waste into Treasure: Utilizing Environment-Pollutant Graphite Tailings as Photocatalyst for Photocatalytic Building Materials

Graphite tailings, as solid waste residuals from graphite extraction and refinement, pose serious risks to the surrounding ecological environment and the safety of residents’ lives. However, it is desirable but challenging how to rationalize the utilization of graphite tailings and further to develop their functionality. Herein, we demonstrate a "turning waste into treasure" strategy: capitalizing on the characteristics of graphite tailings in visible light absorption and rich metal catalytic sites, graphite tailings are employed as photocatalysts and fine aggregates to manufacture photocatalytic building materials, achieving sustainable use. Tailings powder from Luobei, Heilongjiang Province is selected as the photocatalyst, we discover that it exhibits photocatalytic degradation capability for methylene blue (MB) in water under visible-light irradiation: the degradation rates reach 70% within one hour and near-complete degradation within two hours, accompanying good recyclability. Structural analysis reveals that the graphite tailings are enriched with Fe2O3 and TiO2. They are capable of forming type-II heterojunction that enable efficient charge separation and transfer processes, transmitting photogenerated electrons to the active catalytic site to accomplish the photocatalytic degradation of MB. Moreover, other tailings, such as those from Jixi, also achieve photocatalytic degradation of MB, and cement specimens made with graphite tailings also bespoke photocatalytic degradation performance. This work is to provide solutions for the reuse of graphite tailings in the field of functional building materials, and to explore the feasibility of transforming graphite tailings from industrial solid waste to photocatalytic building materials.

A Novel Cold‐Adapted Catechol 1,2‐Dioxygenase From Antarctic Sea‐Ice Bacterium Halomonas sp. ANT108: Characterization and Immobilization

ABSTRACTThe enzyme catechol 1,2‐dioxygenase (CAT) plays a critical role in the biosynthesis pathway of cis, cis‐muconic acid (CCMA), which serves as an indispensable raw material for various industrial applications. In this research, we cloned a novel cold‐adapted CAT (HaCAT) from the Antarctic sea ice bacterium Halomonas sp. ANT108. Homology modeling analysis revealed that HaCAT possessed the characteristic Fe3+ binding site and catalytic active site of typical CATs, and it exhibited unique structural adaptations to cold environments. The optimal temperature and pH for recombinant HaCAT (rHaCAT) were found to be 25°C and 6.5, respectively. At 0°C, the enzyme retained a maximum activity of 43.6%, and in the presence of 1.0 M NaCl, its activity reached 173.9%, demonstrating significant salt tolerance. Additionally, the Vmax and Km of rHaCAT were 6.68 μmol/min/mg and 128.90 μM at 25°C, respectively. Furthermore, rHaCAT was successfully immobilized in the metal‐organic framework ZIF‐8 and retained almost 50% of its activity after five reuse cycles, demonstrating excellent reusability. Overall, these results provided a new resource and theoretical foundation for the industrial biocatalytic production and modification of CAT.

Crystalline/Amorphous Interface Engineering and d-sp Orbital Hybridization Synergistically Boosting the Electrocatalytic Performance of PdCu Bimetallene toward Formic Acid-Assisted Overall Water Splitting.

Advanced electrocatalysts capable of bifunctional catalysis for formic acid oxidation (FAOR) and hydrogen evolution reaction (HER) have garnered significant attention due to their exceptional energy efficiency. In this research, we have meticulously designed a PdCu bimetallene characterized by numerous crystalline/amorphous (c/a) interfaces and robust d-sp orbital hybridization, achieved by integrating the p-block metalloid boron within the PdCu matrix (B-PdCu-c/a). The B-PdCu-c/a bimetallene revealed a multitude of surface atoms and unsaturated defect sites, offering abundant catalytic active sites and an optimized electronic structure. The B2-PdCu-c/a exhibited the best performance in FAOR and HER, achieving a mass activity of 1106 mA mgcat-1 and an overpotential of 52 mV, respectively. Significantly, the two-electrode configuration of B2-PdCu-c/a∥B2-PdCu-c/a attained a low cell voltage of 0.19 V at 10 mA cm-2 during formic acid-assisted overall water splitting. Density functional theory (DFT) calculations indicated that c/a interface engineering and d-sp orbital hybridization synergistically optimized the electronic configuration of pristine PdCu bimetallene. This led to an elevation of the d-band center and an accumulation of charge at the c/a interface, which enhanced the adsorption of intermediates, facilitated C-H bond cleavage, and balanced the adsorption-desorption of hydrogen, thereby improving electrocatalytic activities for FAOR and HER, respectively. This study not only presents a viable strategy for effectively tuning the electronic configuration of bimetallene but also offers valuable insights into the development of electrocatalysts.

Transition Metals Doped into g-C3N4 via N,O Coordination as Efficient Electrocatalysts for the Carbon Dioxide Reduction Reaction.

The electrochemical carbon dioxide reduction reaction (CO2RR) is a potential and efficient method that can directly convert CO2 into high-value-added chemicals under mild conditions. Owing to the exceptionally high activation barriers of CO2, catalysts play a pivotal role in CO2RR. In this study, the transition metal (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) is doped into g-C3N4 with a unique N,O-coordination environment, namely, TM-N1O2/g-C3N4. Herein, the catalytic performance and reaction mechanism for the CO2RR on TM-N1O2/g-C3N4 are systematically investigated by density functional theory methods. Especially, through the calculation of ΔG*H and ΔG*COOH/ΔG*OCHO, the catalysts with preference for the CO2RR over the hydrogen evolution reaction (HER) are selected for further study. Furthermore, Gibbs free energy computation results of each elementary step for the CO2RR on these catalysts indicate that Ti-N1O2/g-C3N4 has significant catalytic activity and selectivity for reducing CO2 to methanol (CH3OH) with the limiting potential (UL) of -0.55 V. Finally, through frontier molecular orbital theory and charge transfer analyses, the introduction of the O atoms illustrates that it is instrumental in regulating the electron distribution of the catalytic active site, thereby improving the catalytic performance. This work provides insight into the design of single-atom catalysts with unique coordination structures for the CO2RR.

The Reduced Barrier for the Photogenerated Charge Migration on Covalent Triazine‐Based Frameworks for Boosting Photocatalytic CO2 Reduction Into Syngas

AbstractPhotocatalytic CO2 reduction together with hydrogen generation is a promising approach to generate syngas, the photogenerated electron migration from photosensitizers to the catalytic active sites is the rate‐determining step. Herein, an integrative strategy is presented by covalently grafting metal complexes into donor–acceptor covalent triazine‐based frameworks. The catalytic active sites are integrated with the photosensitizer units by covalent linkages to form an extended π‐conjugated framework, which significantly reduces the energy barrier for the migration of the photogenerated charge carriers, resulting in high activity and durability in photocatalytic CO2 reduction into syngas under visible light irradiation. The CO and H2 evolution amounts in 1.5 h are 1086 and 1042 µmol g−1, respectively, which greatly surpass those in the host‐guest counterparts. Furthermore, selective adsorption for CO2 over N2 renders this photocatalytic system to be effective for syngas production from the simulated flue gas. This study provides new approaches to construct the integrative photocatalytic systems for solar‐to‐chemical energy conversion.

Two groups and three classes of the conserved structural organization of nucleophile and non-canonical ElbowFlankOxy networks in different superfamily proteins

The nucleophile elbow is a well-known structural motif, which exists in proteins with catalytic triads and contains a catalytic nucleophile and the first node of an oxyanion hole. Here, we show that structural similarities of proteins with the nucleophile elbow extend beyond simple nucleophile elbow motifs. The motifs are incorporated into larger conserved structural organizations, the ElbowFlankOxy networks, incorporating motifs and flanking residues and networks of conserved interactions. A detailed structural analysis shows two major types of ElbowFlankOxy networks, depending on the formation of the oxyanion hole. Additionally, the ElbowFlankOxy networks show three classes: Class 1-2-3, 3-1-2, and 2-3-1, defined by the order in which the catalytic nucleophile and key interacting residues are located in the amino acid sequence, giving rise to six ElbowFlankOxy network variations. This makes it possible to properly position homologous non-catalytic, non-standard, and unusual catalytic triad active sites of proteins with the nucleophile elbow within the fold classification.

Polyoxometalates@Metal-Organic Frameworks: Synthesis Strategies, Nanostructure Modulation and Application in Biomass Conversion.

Polyoxometalates@metal-organic frameworks (POMs@MOFs) have attracted much attention as multifunctional materials in biomass catalysis. Individual POMs and MOFs are hindered by their respective defects, such as poor stability and single catalytic active site, which make it difficult to realize large-scale applications. However, the combination of POMs and MOFs can be used to maximize the catalytic advantages of each. MOFs with high specific surface area and rich pore structure can effectively stabilize and uniformly disperse POMs, while the introduction of POMs also provides more catalytic possibilities for POMs@MOFs. Therefore, POMs@MOFs with ultra-high porosity, large specific surface area and excellent acid catalytic activity have unique catalytic advantages in the field of biomass catalytic conversion. In this work, we provide an overview of the current development of POMs@MOFs in the field of biomass catalysis. The synthesis strategies of POMs@MOFs are summarized and discussed, highlighting the in-situ synthesis methods. We focus on the nanostructure engineering of POMs@MOFs, and explore the "structure-property" relationship in depth. In addition, the representative work of POMs@MOFs in the catalysis of biomass derivatives is summarized. Filially, the prospects, and challenges for the future development of POMs@MOFs in the field of biomass catalysis are also presented.

Strategy for Enhancing Catalytic Active Site: Introduction of 1D material InSeI for Electrochemical CO2 Reduction to Formate.

The presence of oxygen vacancies (Vo) in electrocatalysts plays a significant role in improving the selectivity and activity of CO2 reduction reaction (CO2RR). In this study, 1D material with large surface area is utilized to enable uniform Vo formation on the catalyst. 1D structured indium selenoiodide (InSeI) is synthesized and used as an electrocatalyst for the conversion of CO2 to formate. The electrochemical treatment of InSeI leads to the leaching of Se and I from the catalyst surface and the formation of Vo. The resulting Vo promotes the activity of the CO2RR, which increases the local pH of the catalyst surface and chemically maintains the oxidized metal sites on the catalyst. Owing to these characteristics, activated In wire exhibited remarkable CO2RR activity, thereby surpassing 93% FEformate at 500mA cm-2, with a maximum of 97.3% FEformate at 100mA cm-2. Moreover, the catalytic activity remained consistent for over 50h at 100mA cm-2 (FEformate >88%). Thus, the findings imply that using 1D materials can facilitate the formation of oxygen vacancies on the catalyst surface and improve the selectivity and durability of CO2RR. This indicates the potential for further research on 1D materials as electrocatalysts.

Heterostructuring Uniform 2D CdS on Ru/Ti3C2-TiO2 via In situ Oxidized Ru-Loaded MXene for Boosting Photocatalytic H2 Production.

Building heterojunctions and exposing more catalytic active sites are effective strategies to enhance the photocatalytic hydrogen evolution activity. Herein, TiO2 nanosheets are oxidized in situ on Ru-loaded MXene as carriers and subsequently loaded with uniform 2D CdS via hydrothermal method to obtain 2D Ru/Ti3C2-TiO2/CdS composite photocatalysts that integrate heterojunctions and cocatalysts. The formation of heterojunction between CdS and TiO2 is conducive to promoting the separation and transfer of photogenerated charges, simultaneously, Ru/Ti3C2 with the fully exposed Ru and Ti3C2 can act as effective active sites of photocatalytic hydrogen production reaction. The composite photocatalyst exhibits an improved hydrogen production rate with 5479µmol g-1 h-1, which is 5, 3, and four times more than that of pristine CdS, CdS loaded Ti3C2-TiO2and CdS loaded Ru-TiO2 respectively. The results reveal that the notable enhancement in performance can primarily be ascribed to the introduction of the TiO2/CdS heterojunction and the efficient cocatalysts of Ru/Ti3C2. Moreover, the 2D Ti3C2 with high conductivity as carriers can increase charge transfer, and its 2D structure can serve as a template for growing 2D photocatalysts with higher activity. The interface engineering with multiple interfaces can offer novel insights for the advancement of efficient hydrogen evolution reaction catalysts.

Nitrogen-Rich Molybdenum Nitride with Intrinsic CD39 Nucleotidase Activity.

CD39 is one of the important nucleotidases to adjust extracellular adenosine triphosphate (ATP) and adenosine diphosphate (ADP) concentration. However, the enzyme mimics to simulate the activity of CD39 still remains to be explored. Herein nitrogen-rich molybdenum nitride (Mo5N6) nanosheets are explored to possess CD39-like activity, which are able to catalyze the hydrolysis of the high-energy phosphate bonds (HEPBs) in ATP and ADP but not the common phosphate bonds in adenosine monophosphate (AMP). The catalytic hydrolysis of the phosphate bond over Mo5N6-700 nanosheets is first investigated using para-nitrophenyl phosphate as the model substrate and then the CD39-like activity is further explored and verified by 31p NMR spectroscopy. Mo4+ on the surface of Mo5N6-700 nanosheets are the catalytic active sites. Using ATP as the model substrate, the Km and Vmax values of CD39-like activity at optimal pH 9.0 are 3.2µmol L-1 and 18.5µmol L-1 h-1, respectively. The CD39-like activity of Mo5N6-700 nanosheets enabled the down-regulation of intracellular ATP concentration to a larger degree for cancer cells than normal cells, which makes Mo5N6-700 nanosheets a potential therapeutic reagent for cancers.

Defect Passivation of Mn2+-Doped CsPbX3(X=Cl,Br) Perovskite Nanocrystals as Electrocatalyst for Overall Water Splitting.

Mn doping has been used to improve the physical chemistry of lead halide perovskite nanocrystals such as CsPbX3, where X is a halogen ion. In this paper, a two-phase method for Mn-doped CsPbX3 nanosheets (where X=Br, Cl), namely water-hexane system, is reported. Compared to conventional catalyst arrays, the band gap of CsPbBr3 nanocrystalline is easily tuned, the carrier diffusion distance is remote, the band edge position of the band structure is favorable for a wide range of electrocatalytic redox reactions, and the catalytic active site is maximally exposed, providing a larger electrolyte contact area. The porous hierarchical structure also accelerates the release of hydrogen bubbles. The results showed that the optimized Mn : CsPbBr3 catalyst exhibited excellent electrolytic performance of aquatic hydrogen in alkaline electrolyte (1 mol/L KOH). The overpotentials of the oxygen evolution reaction (OER) at the current densities of 10 and 100 mA cm-2 are only 114.4 and 505.4 mV, respectively, with a Tafel slope of 43 mV dec-1. At a current density of 10 mA cm-2, the excess potential required for the hydrogen evolution reaction (HER) is 158.6 mV and it exhibits excellent electrochemical stability. The Mn : CsPbBr3 nanocrystalline consists of two electrodes for hydrolysis of water, requiring only a voltage of 1.45 V. This provides implications for the optimization of electrocatalysts in alkaline electrolytes with the aim of developing next generation 2D electrocatalysts for overall water splitting.

Honeycomb‐Structured IrOx Foam Platelets as the Building Block of Anode Catalyst Layer in PEM Water Electrolyzer

AbstractAchieving robust long‐term durability with high catalytic activity at low iridium loading remains one of great challenges for proton exchange membrane water electrolyzer (PEMWE). Herein, we report the low‐temperature synthesis of iridium oxide foam platelets comprising edge‐sharing IrO6 octahedral honeycomb framework, and demonstrate the structural advantages of this material for multilevel tuning of anodic catalyst layer across atomic‐to‐microscopic scales for PEMWE. The integration of IrO6 octahedral honeycomb framework, foam‐like texture and platelet morphology into a single material system assures the generation and exposure of highly active and stable iridium catalytic sites for the oxygen evolution reaction (OER), while facilitating the reduction of both mass transport loss and electronic resistance of catalyst layer. As a proof of concept, the membrane electrode assembly in single‐cell PEMWE based on honeycomb‐structured IrOx foam platelets, with a low iridium loading (~0.3 mgIr/cm2), is demonstrated to exhibit high catalytic activity at ampere‐level current densities and to remain stable for more than 2000 hours.

Optimized Dehydrogenation of Magnesium Hydride with Fe and Cu Additives

Solid state hydrogen storage with the use of MgH2 has gained widespread attention because of its good reversible storage capacity. This metal hydride however slowly releases hydrogen at high temperatures ranging between 325 – 375 oC. An important feature required of MgH2 is its ability to commence hydrogen release at a fast rate and reduced temperature. Transition metal-containing alloys/compounds having either Fe or Cu as the principal element have been used to improve the dissociation of hydrogen from MgH2. Studies involving the use of each metal in its elemental form as an additive are minimal. This study investigated the catalytic effects of elemental Fe and Cu on the hydrogen release performance of MgH2 for potential applications in transportation and power generation. It was observed that MgH2/Fe had a better dehydrogenation performance; the temperature of onset of MgH2/Fe and MgH2/Cu dehydrogenation were 205, and 215 oC which were 98 and 88 oC lower than that for as-received MgH2. The highest amount, 1.9 wt. % H2 was released by MgH2/Fe while 1.44 wt. % H2 was released by MgH2/Cu. The activation energy for dehydrogenation was reduced from 150.5 kJ/mol for as-received MgH2 to 89.8 and 79.8 kJ/mol in MgH2/Cu and MgH2/Fe respectively. It took 18.8 min for as-received MgH2 to commence dehydrogenation while that for MgH2/Fe and MgH2/Cu composites started from 12.2 and 13.4 min respectively. The in-situ formed Fe and Cu in MgH2 after milling acted as active catalytic sites for its improved dehydrogenation with MgH2/Fe behaving better.

Honeycomb-Structured IrOx Foam Platelets as the Building Block of Anode Catalyst Layer in PEM Water Electrolyzer.

Achieving robust long-term durability with high catalytic activity at low iridium loading remains one of great challenges for proton exchange membrane water electrolyzer (PEMWE). Herein, we report the low-temperature synthesis of iridium oxide foam platelets comprising edge-sharing IrO6 octahedral honeycomb framework, and demonstrate the structural advantages of this material for multilevel tuning of anodic catalyst layer across atomic-to-microscopic scales for PEMWE. The integration of IrO6 octahedral honeycomb framework, foam-like texture and platelet morphology into a single material system assures the generation and exposure of highly active and stable iridium catalytic sites for the oxygen evolution reaction (OER), while facilitating the reduction of both mass transport loss and electronic resistance of catalyst layer. As a proof of concept, the membrane electrode assembly in single-cell PEMWE based on honeycomb-structured IrOx foam platelets, with a low iridium loading (~0.3 mgIr/cm2), is demonstrated to exhibit high catalytic activity at ampere-level current densities and to remain stable for more than 2000 hours.

Organic-Inorganic Hybrid Perovskite for Ferroelectric Catalysis.

Organic-inorganic hybrid perovskite ferroelectric has gained significant attention for its structural flexibility and diversity. They can directly utilize metal nodes and organic groups as active sites in catalysis. Additionally, their ferroelectric polarization occurs around these active sites, significantly enhancing catalytic activity and demonstrating immense potential for applications. However, their catalytic applications remain underexplored. This work marks the first utilization of the molecular perovskite ferroelectric [3,3-difluorocyclobutylammonium]2CuCl4 (Cu-DFCBA) as a catalyst for alkane oxidation. Under ultrasonic stimulation, it achieved a remarkable turnover number as high as 2402. Compared to inorganic ferroelectrics like lithium niobate (LiNbO3), the molecular ferroelectric exhibited a 1200-fold increase in catalytic activity. This highlights Cu-DFCBA's robust ferroelectric properties and underscores the vast potential of molecular ferroelectrics in catalysis, guiding future system designs.

Stability effects of alumina fibers on SnO2/Al2O3 NFs for efficient electrocatalytic performance towards CO2 reduction reaction

The weak stability of electrocatalysts seriously hinders the practical application in the field of electrocatalytic CO2 reduction reaction (CO2RR), so how to select catalyst supports and realize the ingenious combination between active sites and supports is still a challenge. In this work, alumina fibers (Al2O3 NFs) were employed to support Sn catalytic active sites with the aid of sol-gel methods and electrospinning. As-obtained SnO2-loaded aluminum oxide nanofibers (SnO2/Al2O3 NFs) catalyst possesses bulk-like SnO2 and nano-SnO2 loaded Al2O3 NFs. Interestingly, nano-SnO2 loaded Al2O3 NFs mainly contributes to the superior electrocatalytic properties towards CO2RR, particularly, faraday efficiency of formic acid (FEHCOOH) can reach 72.8% when the potential is -1.264 V, with HCOOH partial current density of 32.76 mA cm-2, and a long-term catalytic stability can be achieved. This study not only provides a new idea for enhancing the stability of electrocatalysts, but also expands the application field of Al2O3 NFs.

NiCo alloy-decorated nitrogen-doped carbon double-shelled hollow polyhedrons with abundant catalytic active sites to accelerate lithium polysulfides conversion

Lithium-sulfur (Li-S) batteries have received significant attention due to their high theoretical energy density. However, the inherent poor conductivity of S and lithium sulfide (Li2S), coupled with the detrimental shuttle effect induced by lithium polysulfides (LiPSs), impedes their commercialization. In this study, we develop NiCo alloy-decorated nitrogen-doped carbon double-shelled hollow polyhedrons (NC/NiCo DSHPs) as highly efficient catalysts for Li-S batteries. The distribution of NiCo alloy on both the inner and outer shells provides abundant catalytic active sites, effectively adsorbing LiPSs, mitigating the shuttle effect, and promoting the conversion between LiPSs and Li2S, even at high sulfur loadings. This results in enhanced redox kinetics within the Li-S system. Moreover, the highly conductive carbon material framework, enriched with carbon nanotubes and graphitic carbon layers, can greatly promote the efficient electron transportation. Additionally, the improved ion diffusion rates benefiting from the hollow structure can also be realized. By harnessing these synergistic effects, Li-S batteries incorporating the double-shelled NC/NiCo DSHP catalysts achieved a high specific capacity of 1310 mAh/g at 0.2C and a superior rate performance of 621 mAh/g at 4C. Furthermore, excellent cycling performance with ultralow capacity fading rate of only 0.045 % per cycle after 800 cycles at 1C was achieved. When sulfur loading reaches 6 mg cm−2, a high capacity of 4.6 mAh cm−2 at 0.1C after 100 cycles further validates the practical potential of this design. This study presents an innovative approach to alloy catalyst design, offering valuable insights for future research of Li-S batteries.

Enhanced Visible‐Light‐Driven Photocatalytic Overall Splitting of Pure Water in a Porous Microreactor

AbstractPhotocatalytic overall splitting of pure water (H2O) without sacrificial reagent to hydrogen (H2) and oxygen (O2) holds a great potential for achieving carbon neutrality. Herein, by anchoring cobalt sulfide (Co9S8) as cocatalyst and cadmium sulfide (CdS) as light absorber to channel wall of a porous polymer microreactor (PP12), continuous violent H2 and O2 bubbling productions from photocatalytic overall splitting of pure H2O without sacrificial reagent is achieved, with H2 and O2 production rates as high as 4.41 and 2.20 mmol h−1 gcat.−1 respectively. These are significantly enhanced than those in the widely used stirred tank‐type reactor in which no O2 is produced and H2 production rate is only 0.004 mmol h−1 gcat.−1. Besides improved charge separation and interaction of H2O with photocatalyst in PP12, bonding interaction of Co9S8 with PP12 creates abundant catalytic active sites for simultaneous productions of H2 and O2, thus leading to the significantly enhanced H2 and O2 bubbling productions in PP12. This offers a new strategy to enhance photocatalytic overall splitting of pure H2O without sacrificial reagent.

Tuning the peroxidase-mimic activity of CuX-trithiocyanuric acid complexes for colorimetric detection of gastric cancer-associated D-amino acids

A cascade colorimetric detection of salivary D-amino acids (DAAs) holds promise for the preliminary screening diagnosis of gastric cancer. Pursuing metal-organic complexes with high peroxidase-mimic (POD-mimic) activity is crucial to enhance diagnosis efficiency. In this work, we developed a straightforward strategy in a “one-pot” process to modulate the POD-mimic activity of CuX-trithiocyanuric acid (CuX-TTCA) complexes. By adjusting the molar ratios of CuX (Cl, Br, and I) and TTCA during synthesis to modify the coordination configuration of Cu(I) in CuX-TTCA, we easily tuned their POD-mimic activities. Among them, CuCl-TTCA-2 with a feeding molar ratio of 2:1 for CuCl:TTCA exhibited remarkable POD-mimic activity attributed to its exposed catalytic active sites and efficient mass transfer ability during catalysis. Long-lived 1O2 was identified as the primary reactive oxygen intermediate. A highly sensitive and selective cascade colorimetric detection platform was developed for two typical DAAs associated with gastric cancer, namely D-proline and D-alanine, achieving limit of detection values of 1.1 and 0.8 μM, respectively. As a proof-of-concept application, our cascade detection platform demonstrated excellent specificity in distinguishing saliva samples between gastric cancer patients and healthy individuals. The outstanding selectivity and reliable outcomes from DAAs assay make our detection platform highly promising for preliminary screening diagnosis of gastric cancer and patient self-detection applications. Our straightforward strategy for tuning POD-mimic activity provides an in-depth understanding on structure-activity relationship in nanozymes, offering valuable opportunities to advance enzyme-mimic optimization for other potential applications.