Insights into the roles of superficial lattice oxygen in formaldehyde oxidation on birnessite

K+-modified birnessite materials were constructed to remove formaldehyde (HCHO) in this work. The introduction of K+ led to weakening of the Mn-O bonds and enhanced the migration of superficial lattice oxygen, resulting in improved redox properties and catalytic activity. MnO2-3K with the largest specific surface area and greatest abundance of superficial lattice oxygen showed the best catalytic performance at 30-130 °C. The operando analyses reveal that HCHO is primarily activated to dioxymethylene (DOM) and subsequently converted to formate species (*COOH). The accumulation of formate species caused a decline in catalytic performance during extended testing at 30 °C, a challenge that could be mitigated by raising the temperature. Theoretical studies disclose that the *COOH → *H2CO3 step with the largest energy barrier is the rate limiting step for HCHO deep decomposition. Molecular oxygen could be activated at oxygen vacancies to replenish the depleted lattice oxygen after decomposition of carbonate species (*H2CO3) and CO2 and H2O desorption. The adsorbed oxygen and water did not limit the deep oxidation of HCHO. This research presents a promising approach for designing highly efficient, non-noble metal catalysts for formaldehyde degradation.

Polylactic acid electrospun membrane loaded with cerium nitrogen co-doped titanium dioxide for visible light-triggered antibacterial photocatalytic therapy

Wound infection caused by multidrug-resistant bacteria poses a serious threat to antibiotic therapy. Therefore, it is of vital importance to find new methods and modes for antibacterial therapy. The cerium nitrogen co-doped titanium dioxide nanoparticles (N-TiO2, 0.05Ce-N-TiO2, 0.1Ce-N-TiO2, and 0.2Ce-N-TiO2) were synthesized using the hydrothermal method in this study. Subsequently, electrospinning was employed to fabricate polylactic acid (PLA) electrospun membranes loaded with the above-mentioned nanoparticles (PLA-N, PLA-0.05, PLA-0.1, and PLA-0.2). The results indicated that cerium and nitrogen co-doping tetrabutyl titanate enhanced the visible light photocatalytic efficiency of TiO2 nanoparticles and enabled the conversion of ultraviolet light into harmless visible light. The photocatalytic reaction under visible light irradiation induced the generation of ROS, which could effectively inhibit the bacterial growth. The antibacterial assay showed that it was effective in eliminating S. aureus and E. coli and the survival rates of two types of bacteria under 30 min of irradiation were significantly below 20% in the PLA-0.2 experimental group. Moreover, the bactericidal membranes also have excellent biocompatibility performance. This bio-friendly and biodegradable membrane may be applied to skin trauma and infection in future to curb drug-resistant bacteria and provide more alternative options for antimicrobial therapy.

Highly Active Amino-Fullerene Derivative-Modified TiO2 for Enhancing Formaldehyde Degradation Efficiency under Solar-Light Irradiation

Formaldehyde (HCHO) is a ubiquitous indoor pollutant that seriously endangers human health. The removal of formaldehyde effectively at room temperature has always been a challenging problem. Here, a kind of amino-fullerene derivative (C60-EDA)-modified titanium dioxide (C60-EDA/TiO2) was prepared by one-step hydrothermal method, which could degrade the formaldehyde under solar light irradiation at room temperature with high efficiency and stability. Importantly, the introduction of C60-EDA not only increases the adsorption of the free formaldehyde molecules but also improves the utilization of sunlight and suppresses photoelectron-hole recombination. The experimental results indicated that the C60-EDA/TiO2 nanoparticles exhibit much higher formaldehyde removal efficiency than carboxyl-fullerene-modified TiO2, pristine TiO2 nanoparticles, and almost all other reported formaldehyde catalysts especially in the aspect of the quality of formaldehyde that is treated by catalyst with unit mass (mHCHO/mcatalyst = 40.85 mg/g), and the removal efficiency has kept more than 96% after 12 cycles. Finally, a potential formaldehyde degradation pathway was deduced based on the situ diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) and reaction intermediates. This work provides some indications into the design and fabrication of the catalysts with excellent catalytic performances for HCHO removal at room temperature.

Visible light in situ driven electron accumulation at the Ti–Mn–O3 sites of TiO2 hollow spheres for photocatalytic hydrogen production

Mn atoms and oxygen vacancies induce the formation of Ti–Mn–O3 sites by visible light-driven, which further regulates the surface potential, visible-light absorption, and carrier separation, resulting in superior H2 evolution.

Photocatalytic Degradation of Deoxynivalenol Using Cerium Doped Titanium Dioxide under Ultraviolet Light Irradiation

Deoxynivalenol (DON) is a major mycotoxin with high toxicity that often contaminates grains, foods and feeds. The traditional approaches for DON removal are difficult to meet industry and agriculture demands due to the high stability of the DON molecule. Therefore, there is an urgent need to develop green and effective strategies for DON degradation. In this study, a batch of photocatalytic nanomaterials of cerium (Ce) doped titanium dioxide (TiO2) were successfully prepared by sol-gel method. The catalysts were systematically characterized by XRD, HRTEM, FT-IR, UV-Vis and XPS. The catalyst 0.5Ce-TiO2 showed superior photocatalytic activity for DON degradation in aqueous solution under ultraviolet light irradiation, better than that of traditional photocatalyst pure TiO2, and 96% DON with initial concentration of 5.0 mg/L could be degraded in 4 h. In addition, the two possible degradation intermediate products C5H8O3 and C17H18O6 were identified, the photocatalytic degradation mechanism and degradation pathway were studied. The results indicate that Ce doped TiO2 photocatalyst can be used to reduce DON effectively.

Boosting visible-light-driven catalytic hydrogen evolution via surface Ti3+ and bulk oxygen vacancies in urchin-like hollow black TiO2 decorated with RuO2 and Pt dual cocatalysts

A novel hollow urchin-like black RuO₂/TiO₂/Pt nanomaterial with surface Ti³⁺ and bulk single-electron oxygen vacancies (Vo·) was used for enhancing the hydrogen evolution performance under visible light.