Constructing multi-functional active sites in heterogeneous catalysts and harnessing their synergistic effects are crucial for efficiently converting CO2 into high-value chemicals. Here, we report an inverse ZrO2/Cu catalyst featuring precisely engineered Zr3+-O-Cu interfaces, significantly improving CO2-driven N-methylation of amines. The optimized catalyst achieves remarkable catalytic performance, demonstrating an aniline conversion of 98.0 % with an impressive N-methylaniline selectivity of 97.4 %, sustained robustly over 10 reaction cycles under mild reaction conditions. The exceptional performance was attributed to the interactions between interfacial Zr3+ and Cu sites, stabilizing the reactive intermediate and enhancing the synergistic activation of CO2 and aromatic amines. Comprehensive experimental analyses and detailed theoretical calculations elucidated a preferential C-N coupling mechanism, effectively guiding the reaction towards mono N-methylation and bypassing the need for active intermediates such as formate and formaldehyde. This study establishes a sustainable route for CO2 fixation and delivers pivotal insights for rationally designing interfacial catalytic systems.

Catalytic conversion of CO2 to light aromatics (including benzene, toluene, and xylene, collectively known as BTX) and olefins is an eco-friendly approach for reducing waste gas emissions, but it remains a significant challenge. Traditional methods that modify the surface acid sites of zeolites to increase BTX selectivity often produce undesired byproducts and involve complex preparation processes. Here, we report a strategy to enhance BTX formation by altering the reaction intermediates using a tandem catalyst composed of metal oxides and dualzeolite (GaZrOx/SAPO-34/ZSM-5, labelled as GZO/S34/Z5). The inclusion of S34 zeolite facilitates the partial transformation of CO2 hydrogenation intermediates produced by GZO into light olefins, thereby promoting the aromatic formation in Z5. This results in a 72.6% selectivity for total aromatics in hydrocarbons, with BTX accounting for a significantly higher selectivity compared to GZO/Z5, representing a 3.4-fold increase from 7.1% to 24%. Additionally, by regulating the acid density of Z5, the tandem catalyst with dual-zeolite can directly convert CO2 and H2 to 53.5% aromatics and 25.5% olefins, with a BTX selectivity of 13.8% in hydrocarbons. This tandem catalyst design, through adjusting the reaction intermediates, offers an efficient method to inhibit the formation of light paraffin byproducts and enhance BTX selectivity in CO2 conversion.

Photoelectrochemical cathodic protection for metals, leveraging the unique photoelectrochemical properties of TiO2 semiconductor films, represents an innovative approach to corrosion protection with promising potential. However, pure TiO2 films exhibit limitations, including low visible light absorption, rapid recombination of photogenerated electrons and holes, and low photoelectric conversion efficiency. To enhance the photoelectrochemical properties of TiO2 film photoanodes, composite films are essential. In this study, a g-C3N4 layer and Ag nanoparticles were sequentially deposited onto an anodized TiO2 nanotube array film on a Ti foil via simplified chemical vapor deposition and chemical bath deposition, respectively, to enhance the TiO2 composite film's photoelectrochemical performance for metal cathodic protection applications. The results demonstrated substantial improvements in light absorption and photoelectrochemical performance for the Ag/g-C3N4 co-sensitized TiO2 nanotube composite film compared to the pure TiO2 nanotube array film. The Ag/g-C3N4/TiO2 composite film's light absorption was extended into the visible light spectrum, enhancing the separation efficiency of photogenerated electrons and holes. Under white light irradiation, the photocurrent density of the composite film in an aqueous solution containing 50% (volume fraction) ethylene glycol and 0.2 mol/L NaOH reached 135 mu A/cm(2), approximately 11 times that of the pure TiO2 film. Furthermore, when employed as a photoanode, the composite film on the Ti surface reduced the electrode potential of 403 stainless steel in a 0.5 mol/L NaCl solution by 530 mV relative to the steel's free corrosion potential, demonstrating a notably enhanced photoelectrochemical cathodic protection effect.

The direct conversion of CO2 to aromatics using tandem catalysts presents an efficient approach to mitigating carbon emissions. Although composite oxide-zeolite tandem systems via methanol intermediates exhibit high selectivity toward aromatics, they feature moderate levels of CO2 conversion due to challenges in CO2 activation, particularly in understanding the role of metal hydride species. In this study, we synthesized stable GaZrOx composite oxides and identified the critical function of Ga-H species under hydrogen-rich conditions. Our findings demonstrate that high coverage of Ga-H species on the GaZrOx surface facilitates the formation of HCOO* intermediates, thereby enhancing selectivity toward aromatics when integrated with the ZSM-5 zeolite. Unlike the previous reports, our data reveal that the homolytic dissociation of hydrogen, triggered by an initial heterolytic process, serves as the dominant mechanism, boosting the space-time yield of aromatics by 2.3 times and achieving a CO2 conversion of 14.3% and 82.8% selectivity for aromatics under optimized conditions. However, a high Ga/Zr molar ratio leads to the formation of the Ga-Ga bond, which reduces the selectivity of aromatics. These insights into the behavior of Ga-H species through homolytic dissociation offer a potential framework for designing efficient tandem systems composed of composite oxides and ZSM-5 in the hydrogenation of CO2 to aromatics.

Selective methylation of aromatics using CO2/H-2 presents a promising avenue for producing high-value-added chemicals with high selectivity. Herein, we introduced atomically dispersed Pd species into ZnZrOx solid solution and combined with HZSM-5 to create a bifunctional catalyst, applying to selectively synthesize para-xylene through toluene methylation using CO2/H-2 at low pressure. Remarkably, 0.1 wt% Pd in PdZnZrOx-HZSM-5 afforded the selectivity of xylene in CO-free products and para-xylene in xylene to 90.0% and 85.6% at 0.5 MPa, respectively. Spectroscopic characterizations revealed that atomically dispersed Pd species enhance the dissociation of adsorbed hydrogen and facilitate the creation of oxygen vacancies, benefiting the CO2 hydrogenation to CHxO intermediates. Density functional theory calculations suggested that Pd-doped ZnZrOx reduces the energy barrier for hydrogenating H2COOH* to H2CO*, aiding to form CH3O* intermediate for toluene methylation. This work provides insights into the design of catalysts for the selective methylation of aromatics using CO2/H-2 at low pressure.

Direct N-alkylation of amines, such as piperazine, with alcohols via photocatalysis is a promising method, where the incorporation of metal nanoparticles (NPs) into photocatalysts significantly influences catalytic performance. Here, we report TiO2 photocatalysts impregnated with various NPs using the photodeposition method (labelled as M/TiO2, where M includes Pt, Pd, Au, Ag, Cu, and Co) for the N-methylation of piperazine with methanol. Specifically, Pt/TiO2 and Pd/TiO2 catalysts achieved conversions of 64.3% and 50.9%, respectively, within 4 h, displaying distinct selectivities. Pt/TiO2 predominantly yielded enamine intermediate with a selectivity of 95.4%, while Pd/TiO2 mainly produced N-methylpiperazine with a selectivity of 83.6%. Through comprehensive characterizations and control experiments, we found that both Pt NPs and Pd NPs enhance the light absorption and promote photogenerated electron-hole separation. However, Pd NPs facilitate the formation of Pd-H active species and contain more sites for the adsorption of enamine, thereby favoring the hydrogenation of the enamine intermediate to produce N-methylpiperazine. This study underscores the pivotal role of metal NPs in modulating the outcomes of photocatalytic N-methylation reactions on TiO2.

Cyanobacterial blooms pose a serious challenge to ecosystems and human health. Photocatalysis, as an advanced green oxidation technology, has potential applications in cyanobacteria removal. In this paper, Zn/g-C3N4 photocatalysts with different mass ratios were prepared for algal inactivation. In 3 h, the best performance comes from the experiment using 10% Zn/g-C3N4 photocatalyst, which inactivated 80% of microcystis aeruginosa (9x10(6) similar to 10x10(6) cells/mL) when exposed to visible light. Secondly, the potential mechanism of the photocatalytic inactivation of microcystis aeruginosa was proposed in combination with the generation of reactive oxygen species and the leakage of the algal cell contents. The photocatalyst first covered the surface of the algal cells to stop their movement; then the catalyst was excited under light and destroyed the outer protective structures of the cells (cell membrane, cell wall, and organic membrane, etc.) through the action of reactive oxygen species (O-1(2) and (OH)-O-center dot) generated by Zn/g-C3N4, leading to structural changes in the outer layer of the cells. And then photocatalytic oxidation of the intracellular cytoplasm led to the loss of its physiological functions (via losing of inorganic ions and non-electrolytes, etc.). Finally the cell is inactivated or decomposed. This understanding may provide theoretical and practical implications for the prospects of harmful algal control.

Hexamethylene diamine, an important chemical intermediate for polyamides, can be synthesized through the two-step route of caprolactam (CPL) ammonolysis to 6-aminocapronitrile (ACN), followed by hydrogenation. This method has received increasing attention from academia and industry. However, studies on the catalyst structure-performance correlation in CPL ammonolysis are still sporadic. In this work, a series of anatase TiO2 with different oxygen vacancy concentrations was prepared by chemical reduction using NaBH4. The oxygen vacancy on TiO2 surface, presented as Ti3+ sites, substantially enhances the adsorption and activation of NH3, which are demonstrated as the key steps in ammonolysis. Owing to the synergistic effect of Ti3+ and Ti4+ species, the CPL conversion rate and ACN selectivity of 85 and 97%, respectively, are achieved within 250 h. Density functional theory calculations showed that the intermediates on oxygen vacancy-rich TiO2 had a more favorable adsorption energy compared to those on intact TiO2, which is in good agreement with the experimental results.

Aristolochic acid (AA) has strong carcinogenicity, and it has been reported that the medicinal and edible plant Houttuynia cordata may contain AA. Among transition metals, nickel and iron have outstanding catalytic ability for nitro reduction. The multivalent NiFe2O4 (NFO), which effectively promotes the redox reaction, has become a promising electrochemical material. In this work, we innovatively used a one-pot hydrothermal method to prepare NFO in situ on the surface of carbon nanotubes. For the first time, the composite NiFe2O4@MWCNTs (NFO@CNTs) was utilized to build a sensitive electrochemical sensor for detecting AA. The NFO@CNTs/GCE exhibited strong electrochemical performance due to the synergistic effect of high catalytic activity of NFO and good conductivity of carbon nanotubes. Furthermore, in order to provide a basis for the safe use of Houttuynia cordata, the electrochemical senor was successfully applied to detect AA in Chinese herbal medicines, confirming its practicability in real samples. This work broadens the application of nickel ferrite, which is expected to be a new candidate material for sensors.

As the most common cyanobacterial toxin, microcystin LR (MC-LR) has dangerous neurotoxicity and hepatotoxicity, posing a serious threat to human and ecosystem health. Therefore, we constructed a type-II CeO2/g-C3N4 heterojunction for highly efficient degradation of MC-LR via peroxymonosulfate (PMS) assisted-visible light-driven photocatalysis process. Multi techniques were conducted to analyze the microstructures, optical and electrochemical properties of CeO2/g-C3N4. The experimental results indicate that the composite material has appropriate energy levels and establishes a well-established interfacial band structure, facilitating the migration and separation of photogenerated electron-hole pairs. The coupled photocatalysis and PMS activation system presented a dramatically enhanced catalytic performance. Within 60minutes, 10% CeO2/g-C3N4/PMS could degrade 99% of the MC-LR present in the solution under visible light irradiation, which was about 3.8 times higher than that in a single photocatalytic system. The optimal conditions for this degradation process were a PMS dosage of 3.0mM and an initial pH of 2.5. EPR analysis revealed that SO4•ˉ, O2•ˉ, h+, and 1O2 were involved in the degradation process. Moreover, the intermediates of its degradation were analyzed through UPLC-MS. This study provides a valuable resource for the intelligent development of type-II heterojunction and its practical implications in the photodegradation of MC-LR through synergistic activation with PMS.

N-methylation of amines using CO2 and H-2 addresses the problems of expensive raw materials and harsh reaction conditions. However, designing a high-active and stable interface for the efficient preparation of monomethyl amine compounds in this tandem reaction remains a challenge to be overcome. Here, Cu-ZrOx composites are dispersed on SBA-15, silicalite-1, and ZSM-5 through the oxalic acid precipitation method for the N-methylation of amines using CO2 and H-2. Results show that the dispersion of Cu-ZrOx on the surface of SBA-15 is superior to the other two molecular sieves and effectively prevents the sintering of active metals. A 20 wt% Cu-ZrOx/SBA-15 catalyst proves to be optimal for the N-methylation of aniline (AN) using CO2 and H-2 to methylaniline (MA) and the catalyst performance remains stable after 5 cycle runs. The optimal catalyst exhibits an AN conversion of 97.6% and a selectivity of 96.5% for MA under the conditions of 180 degrees C, 4.0 MPa (H-2/CO2/N-2 = 72/24/4, molar ratio), and 8 h. Spectroscopic investigation and controlled experiments indicated that the preferential adsorbed AN on the catalyst surface reacts with CO2 to generate C-N bond, thereby avoiding the self-coupling side reaction of AN and achieving a high yield of 94.2% for MA.

Harmful algal blooms and the release of cyanotoxins pose a significant threat to aquatic life. This study aimed to develop a high efficient way to degrade microcystin-LR (MC-LR), a most common and highly toxic cyanotoxin in cyanobacterial blooms, by constructing a Z-scheme ZnO-g-C3N4 heterojunction for photocatalysis integrated with permonosulfate (PMS) activation process. The formation of the Z-scheme heterojunction facilitated the separation of photogenerated carriers and generated more active species with strong oxidative potential, resulting in more efficient degradation of MC-LR. Under visible light, the ZnO/g-C3N4/PMS photocatalyst successfully removed 97% of MC-LR (500 mu g center dot L-1) within 120 min. In comparison, the ZnO/g-C3N4/PMS (k = 0.074 min(-1)) system exhibited degradation rate constants of 8.6 and 11.7 times higher than that of g-C3N4/PMS (k = 0.0086 min(1)) and ZnO/PMS (k = 0.0063 min (-1)) systems, respectively. Chemical trapping experiments and EPR tests revealed that the predominant active species were center dot O-2, SO4 center dot-, and center dot OH. The degradation route of MC-LR by ZnO/ g-C3N4/PMS/Vis process was proposed based on the intermediate products analysis by UPLC-MS, wherein the addition of center dot OH and the oxidative cleavage by center dot O-2 and SO4 center dot-were the main degradation pathways. This study developed a prospective way to design Z-scheme heterojunction photocatalyst constructing with PMS activation for highly efficient prevention of harmful algal blooms.

A highly efficient g-C3N4/SrTiO3 co-decorated rutile TiO2 nanorod composite film photoanode was fabricated on a conductive glass substrate by a three-step synthesis process involving hydrothermal reactions and chemical vapor deposition. The g-C3N4/SrTiO3/TiO2 composite film with an appropriate cascade energy band structure showed greatly improved visible light absorption and exhibited 4.5 times higher photocurrent density than the undecorated TiO2 film, resulting from its higher separation and transfer efficiency of the photogenerated electron-hole pairs. Under the white light irradiation, the composite film photoanode made the potential of the coupled 403 stainless steel in a 0.5 M NaCl solution decrease by 680 mV from its free corrosion potential, showing a significantly enhanced photoelectrochemical cathodic protection effect.

Phenol amination to various valuable amines has attracted considerable attention in heterogeneous catalysis, but limited studies have focused on non-noble metal catalysts. This study reports a bifunctional catalyst (Ni/SiO2-AE) containing nickel nanoparticles and Lewis acid sites derived from nickel phyllosilicates for efficient amination of phenol to cyclohexylamine. The Ni/SiO2-AE catalyst resulted in 89.4% phenol conversion and 86.0% selectivity to cyclohexylamine at 160 degrees C for 2 h, which outperforms the catalysts by conventional deposition-precipitation (Ni/SiO2-DP) and wetness-impregnation (Ni/SiO2-WI). The turnover frequencies based on the actual exposed metal surface area for Ni/SiO2-AE, Ni/SiO2-DP, and Ni/SiO2-WI are calculated as 71.7, 49.0, and 8.7 h(-1), respectively. Results demonstrate that the Ni nanoparticles exsoluted from nickel phyllosilicates participate in the activation of dihydrogen molecules, and the Lewis acid sites stemmed from coordination unsaturated Ni2+ sites on the catalyst serve to adsorb and activate phenol. The synergistic effect of the dual-functions intensifies the phenol amination.

The catalytic synthesis of ethanol directly from syngas is one of the most attractive routes due to its cost-effectiveness and the high demand for ethanol. However, progress is critically stagnant due to the limited activity and ethanol selectivity of the catalysts. Here, La-Rh-Co/ZrO2 nanoscaled catalysts derived from ZrO2-supported LaRhxCo1-xO3 perovskite nanostructures were prepared by citric acid complexing followed by calcination and reduction. Rh and Co species derived from the precursors can increase the amount of interfacial species and construct the active sites for the direct synthesis of ethanol from syngas. Co species were proven to be confined in the ZrO2 matrix, with high-valent Co delta+ derived from LaCoOx. These Co species can decorate Rh species by forming an interface, Rh0-Rh+-O-Co delta+, as confirmed by extended X-ray absorption fine structure, resulting in a higher molar fraction of Rh+. The formed intimate Rh0-Rh+- O-Co delta+ active sites originating from the interfaces are conducive to CO dissociation and CO insertion, leading to an impressive ethanol selectivity of 55.7% and a high CO conversion of 33.5% with good stability over the La-Rh-Co/ZrO2 nanoscaled catalysts. The results show that the strategy of interfacial construction enables the design of robust catalysts to break the scale relationship between conversion and selectivity.

In this work, Bi2S3 and CdSe were used to modify a TiO2 nanotube film for obtaining a Bi2S3/CdSe/TiO2 composite film with enhanced photoelectrochemical performance. The TiO2 nanotube array film was fabricated on a Ti foil by anodic oxidation. CdSe was formed on the TiO2 nanotube film by constant current electrodeposition, and then Bi2S3 was prepared on the binary CdSe/TiO2 composite film by successive ionic layer adsorption and reaction to obtain a Bi2S3/CdSe co-modified TiO2 nanotube composite film with a cascade band structure. The results showed that the Bi2S3/CdSe/TiO2 nanotube composite film showed enhanced photoabsorption in the visible light range, and its photoelectrochemical performance was greatly improved. Under white light illumination, the photocurrent density of this ternary composite film reached 670 mu A.cm(-2), which was about 17.6 times that of the TiO2 nanotube film. The Bi2S3/CdSe/TiO2 composite film could provide excellent photoelectrochemical cathodic protection for 403 stainless steel (403SS) in a 0.5 mol.L-1 NaCl solution, and reduced the potential of 403SS by 690 mV relative to its corrosion potential.

A novel Bi2S3/reduced graphene oxide (rGO) co-modified TiO2 nanotube photoanode was fabricated on a Ti foil by anodization combined with cyclic voltammetric electrodeposition, and successive ionic layer adsorption and reaction. After modifying the TiO2 nanotube film with rGO sheets and Bi2S3 nanoparticles, the band gap of the Bi2S3/rGO/TiO2 composite film decreased, and its photoresponse was extended to the visible region. Under white light irradiation, the composite film in a 0.1 M Na2SO3 and 0.1 M Na2S solution exhibited 62.5 times higher photocurrent density than the TiO2 film. The composite film photoanode could make the potential of the coupled 403 stainless steel in a 0.5 M NaCl solution negatively shift by 490 mV, showing enhanced photoelectrochemical cathodic protection.

In order to obtain a TiO2 nanocomposite film with enhanced photoelectrochemical properties for corrosion protection of metals, a TiO2 nanotube film was fabricated on a Ti substrate via anodization, then ZnIn2S4 nanosheets and CdSe nanoparticles were sequentially deposited on the TiO2 film by hydrothermal treatment and electrodeposition, respectively. The CdSe/ZnIn2S4 co-modified TiO2 heterostructured nanocomposite film showed remarkably enhanced visible light absorption and photoelectrochemical properties. Under white light irradiation, the photocurrent density of the nanocomposite film in the mixed solution with 0.1 M Na2S and 0.1 M Na2SO3 was 33 times higher than that of the TiO2 film. The nanocomposite could negatively shift the potential of the coupled 403 stainless steel immersed in a 0.5 M NaCl solution by 440 mV, showing efficient photoelectrochemical cathodic protection.

A TiO2 nanotube film was fabricated on a Ti foil via anodization, SnO2 quantum dots were deposited on the film by hydrothermal treatment, and then Ag nanoparticles were formed on the SnO2/TiO2 film by pulse electro-deposition to obtain a Ag/SnO2 co-modified TiO2 composite photoanode with good photocathodic protection performance and charge storage ability. The properties of the composite film were investigated by surface analyses, UV-vis and fluorescence spectroscopies, and photoelectrochemical measurements. The results showed that the light absorption of the Ag/SnO2/TiO2 film was extended into the visible region compared with the TiO2 film. The photocurrent intensity of the composite film was two times as high as that of the TiO2 film. The composite photoanode under illumination by white light made the potential of the coupled 403 stainless steel (403SS) in a 0.5 M NaCl solution drop by 475 mV in contrast with its corrosion potential, showing an enhanced photocathodic protection effect. It is noteworthy that the 403SS potential was still 270 mV lower than the corrosion potential within 22.5 h after cutting off the illumination, demonstrating that the cathodic protection could be maintained through the charge storage ability of the composite photoanode.

Photocathodic protection by TiO2 semiconductor materials for metals has interested many corrosion researchers for years. However, a pure TiO2 semiconductor anode can only absorb ultraviolet light and cannot maintain the photocathodic protection in the dark. This has limited its practical applications to a great extent. Overcoming these limitations is significant as well as challenging. Therefore, the objective of this work is to prepare a modified TiO2 composite film with visible light absorption and charge storage capabilities for application in photocathodic protection. First, we fabricated an ordered TiO2 nanotube array film on a Ti substrate by electrochemical anodization. Then, we prepared NiO nanoparticles on the film via a hydrothermal reaction to obtain a p-n heterostructured NiO/TiO2 nanotube array composite film. The properties of the prepared films were investigated by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis absorption spectroscopy, photoluminescence spectroscopy, and photoelectrochemical techniques. The results indicated that the electrochemically anodized TiO2 film had an anatase phase structure and consisted of vertically ordered nanotubes with an inner diameter of about 80 nm and length of 250 nm. After the NiO nanoparticles were deposited on the film, the TiO2 nanotube array structure remained intact. The main phase of TiO2 was still anatase, but the light absorption of the NiO/TiO2 composite film was extended into the visible region, which was in contrast to that of the simple TiO2 film. Moreover, the composite film showed lower photoluminescence intensities than the TiO2 film, implying that a higher charge carrier separation efficiency could be achieved by modification with NiO. Under white light illumination, the photocurrent density of the NiO/TiO2 composite film in a mixed solution of 0.5 mol.L-1 KOH and 1 mol.L-1 CH3OH reached 176 mu A.cm(-2), which was 2 times higher than that of the simple TiO2 nanotube film, indicating that the composite film had improved photoelectric conversion efficiency and photoelectrochemical properties. The potential of 403 stainless steel (403SS) in 0.5 mol.L-1 NaCl solution decreased by 380 and 440 mV relative to its corrosion potential when coupled to the TiO2 film and NiO/TiO2 composite film, respectively, under white light illumination. This indicated that the heterostructured NiO/TiO2 film as a photoanode could produce more effective photocathodic protection on the steel as compared with the pure TiO2 film. Even after 2.5 h of illumination, the composite film could continuously provide photocathodic protection to 403SS for about 15.5 h in the dark, suggesting that the NiO/TiO2 composite film had a charge storage capability that was significant for its practical applications.