Integrating photocatalytic reduction of CO2 with selective oxidation of tetrahydroisoquinoline over InP–In2O3 Z-scheme p-n junction

Decorating of 2D indium oxide onto 2D bismuth oxybromide to enhance internal electric field and stimulate artificial photosynthesis

CO2 photocatalytic reduction is an excellent strategy for promoting solar-to-chemical energy conversion and alleviating the severe environmental crisis. In this study, 2D indium oxide (IO) is decorated on 2D bismuth oxybromide (BOB) nanosheets to gain BOB/IO (BxIy) heterojunction. The optimal B3I1 composite affords a CO production rate of 54.2 μmol⋅g-1, about 2.2 times and 11.3 times higher than those of the pristine BOB and IO, respectively. The introduction of IO significantly enhances the internal electric field (IEF), leading to accelerated charge transfer and prolonged lifetime of the photogenerated carriers. In the BxIy composite, the BOB and IO serve as the electron acceptor and donor, respectively, facilitating the reduction of CO2 and oxidation of H2O. In-situ DRIFTs spectra are used to confirm the catalytic active sites and provide insights into the mechanism of CO2 photoreduction. The results suggest *COOH and *CO2- species played a crucial role in the formation of CO. This work presents a valuable perspective on understanding the charge transfer route and developing highly efficient photocatalysts for CO2 photoreduction.

Simultaneous Photocatalytic Tetracycline Oxidation and Cr(VI) Reduction by Z-Scheme Multiple Layer TiO2/SnIn4S8

Wastewater pollutants are a major threat to natural resources, with antibiotics and heavy metals being common water contaminants. By harnessing clean, renewable solar energy, photocatalysis facilitates the synergistic removal of heavy metals and antibiotics. In this paper, MXene was both a template and raw material, and MXene-derived oxide (TiO2) and SnIn4S8 Z-scheme composite materials were synthesized and characterized. The synergistic mode of photocatalytic reduction and oxidation leads to the enhanced utilization of e-/h+ pairs. The TiO2/SnIn4S8 exhibited a higher photocatalytic capacity for the simultaneous removal of tetracycline (TC) (20 mg·L-1) and Cr(VI) (15 mg·L-1). The main active substances of TC degradation and Cr(VI) reduction were identified via free radical scavengers and electron paramagnetic resonance (EPR). Additionally, the potential photocatalytic degradation route of TC was thoroughly elucidated through liquid chromatography-mass spectrometry (LC-MS).

Photochemical reduction of CO2 into CO coupling with triethanolamine decomposition

In this work, the impacts of triethanolamine (TEOA) on the performance of photochemical CO2 reduction were investigated in a simple homogeneous system. We demonstrates that CO2 can be converted into CO coupling with the decomposition of triethanolamine in TEOA aqueous solution without other additives under light irradiation. About 7.5 μmol CO product is achieved within 7 h with a maximum apparent quantum yield (AQY) of 0.086% at 254 nm. The isotope labelling experiment confirms that CO product originates from the reduction of CO2 rather than the decomposition of TEOA. In addition, the photochemical system exhibits excellent stability, no obvious inactivation is observed during long-term photochemical CO2 reduction reaction. This work provides a deep understanding of the effects of TEOA on the performance of photocatalytic CO2 reduction. Upon utilizing TEOA as a sacrificial electron donor in photocatalytic system, the contribution of TEOA must be considered once evaluating the catalytic activity of catalysts.

Branched Porous Ni3N as a Catalytic Electrode for Selective Semidehydrogenation of Tetrahydroisoquinoline

Oxygen evolution in electrochemical water splitting needs a high overpotential that significantly reduces the energy efficiency. To explore an alternative anodic reaction to promote the production of hydrogen at the other end of water splitting and at the same time to get high-value-added chemicals is highly desirable. Herein, we demonstrate a novel branched porous Ni3N catalyst that is prepared for dehydrogenation of tetrahydroisoquinoline, which acts as an anodic oxidation reaction to promote H2 formation on the other end. Interestingly, the Ni3N catalytic electrode can induce effective semidehydrogenation with the selective formation of dihydroisoquinoline, which is difficult to be obtained by the usual direct synthesis route. The catalytic electrode exhibits a low potential of 1.55 V (vs RHE) for a catalytic current density of 61 mA cm-2 with dehydrogenation of tetrahydroisoquinoline and hydrogen production. In situ Raman spectra studies suggest that NiOOH is formed on the electrode surface, which mediates the oxidation semidehydrogenation process. This work also provides a strategy to fabricate nitride materials for applications beyond selective semidehydrogenation of tetrahydroisoquinoline.

Photocatalytic CO2 Reduction Coupled with Alcohol Oxidation over Porous Carbon Nitride

The photocatalytic transformation of CO2 to valuable man-made feedstocks is a promising method for balancing the carbon cycle; however, it is often hampered by the consumption of extra hole scavengers. Here, a synergistic redox system using photogenerated electron-hole pairs was constructed by employing a porous carbon nitride with many cyanide groups as a metal-free photocatalyst. Selective CO2 reduction to CO using photogenerated electrons was achieved under mild conditions; simultaneously, various alcohols were effectively oxidized to value-added aldehydes using holes. The results showed that thermal calcination process using ammonium sulfate as porogen contributes to the construction of a porous structure. As-obtained cyanide groups can facilitate charge carrier separation and promote moderate CO2 adsorption. Electron-donating groups in alcohols could enhance the activity via a faster hydrogen-donating process. This concerted photocatalytic system that synergistically utilizes electron-hole pairs upon light excitation contributes to the construction of cost-effective and multifunctional photocatalytic systems for selective CO2 reduction and artificial photosynthesis.

Conductive polymer mediated earth abundant Z-scheme g-C3N4/Fe2O3 heterostructure with excellent photocatalytic activity

Being the second most abundant metal in the surface of the earth (5.1%), the size confined iron-based photocatalyst is of especially importance for solar energy conversion. Herein, the ternary Z-scheme...

Photo-electro-Fenton-like process for rapid ciprofloxacin removal: The indispensable role of polyvalent manganese in Fe-free system

The residual ciprofloxacin (CIP) in water seriously menaces the ecological safety and public health. Here, a Fe-free photo-electro-Fenton-like (PEF) system was designed for efficient degradation of CIP in water. A Z-scheme MnO_x/g-C₃N₄ (MCN) nanocomposite with low-cost, large specific surface area and abundant active sites was successfully synthesized as a photoelectric catalyst. The XPS analysis indicated the presence of Mn²⁺, Mn³⁺ and Mn⁴⁺ in the MCN (1:6) composite, and the conversion among polyvalent manganese made the decomposition of H₂O₂ more efficient. Therefore, the manganese ions replaced the Fe element in traditional Fenton system. With the MCN (1:6), the PEF system could also produce O₂^-, OH and h⁺ under the visible light irradiation. The synergetic excitation of multiple active species promoted the rapid decomposition of CIP. Besides, the polyvalent property of manganese oxide resulted in the presence of oxygen vacancies which could improve the electrocatalytic reactivity of the catalyst. Finally, the degradation efficiency of CIP was 96.23% in 120 min and the mineralization efficiency was 80.02% in 240 min.

Tuning Crystallinity and Surface Hydrophobicity of a Cobalt Phosphide Cocatalyst to Boost CO2 Photoreduction Performance

Photocatalytic CO₂ conversion is a promising method to yield carbon fuels, but it remains challenging to regulate catalytic materials for enhanced reaction efficiency and tunable product selectivity. This study concerns the development of a facile and efficient thermal post-treatment method to improve the crystallinity and surface hydrophobicity of a cobalt phosphide (CoP) cocatalyst, which promotes the separation and transfer of photoexcited charge carriers, reinforces CO₂ chemisorption, and weakens the H₂ O affinity. Compared with pristine CoP, the optimal CoP-600 cocatalyst displays a 3.5-fold enhancement in activity and a 2.3-fold increase in selectivity for the reduction of CO₂ to CO with a high rate of 68.1 μmol h^-1 .

Unveiling the Activity Origin of Iron Nitride as Catalytic Material for Efficient Hydrogenation of CO2 to C2+ Hydrocarbons

Developing efficient catalytic materials and unveiling the active species are significant for selective hydrogenation of CO₂ to C₂₊ hydrocarbons. Fe₂ N@C nanoparticles were reported to exhibit outstanding performance toward selective CO₂ hydrogenation to C₂₊ hydrocarbons (C₂₊ selectivity: 53.96 %; C₂ -C₄ ⁼ selectivity, 31.03 %), outperforming corresponding Fe@C. In situ X-ray diffraction, ex situ Mössbauer and X-ray photoelectron spectra revealed that iron nitrides were in situ converted to highly active iron carbides, which acted as the real active species. Moreover, the combined results of in situ diffuse reflectance infrared Fourier transform spectroscopy and control experiments suggested an in situ formed carbonyl iron-mediated conversion mechanism from iron nitrides to iron carbides.

Cobalt ion redox and conductive polymers boosted the photocatalytic activity of the graphite carbon nitride–Co3O4 Z-scheme heterostructure

The enhanced photocatalytic hydrogen evolution performance of g-C₃N₄–Co₃O₄ 2D–1D Z-scheme heterojunctions was achieved through the synergistic effect of the cobalt ion redox, conductive polyaniline, and a Co₃O₄ nanobelt.

A Z-scheme ZnIn2S4/Nb2O5 nanocomposite: constructed and used as an efficient bifunctional photocatalyst for H2 evolution and oxidation of 5-hydroxymethylfurfural

A bifunctional Z-scheme ZnIn₂S₄/Nb₂O₅ photocatalyst was fabricated, which can be used both for hydrogen evolution and HMF oxidation.

Charge separation and molecule activation promoted by Pd/MIL-125-NH2hybrid structures for selective oxidation reactions

The Pd/MIL-125-NH₂hybrid photocatalyst exhibits great advantages in charge separation and molecule activation, with sufficient generation of both superoxide radical and singlet oxygen toward selective oxidation of organic molecules.