查看更多>>摘要：3D-printing (also known as additive manufacturing) has recently emerged as an appealing technology to fight against the mainstream use of carbon-based fossil fuels by the large-scale, decentralized, and sustainable manufacturing of 3D-printed electrodes for energy conversion devices. Although promising strides have been made in this area, the tunability and implementation of cost-effective metal-based 3D-printed electrodes is a challenge. Herein, a straightforward method is reported to produce bimetallic 3D-printed electrodes with built-in noble metal catalysts via galvanic replacement. For this goal, a commercially available copper/polylactic acid composite filament has been exploited for the fabrication of Cu-based 3D-printed electrodes (3D-Cu) using fused filament fabrication (FFF) technology. The subsequent electroless deposition of an active noble metal catalyst (viz. Pd) onto the 3D-Cu surface has been carried out via galvanic exchange. A detailed electrochemical study run by scanning electrochemical microscopy (SECM) has revealed that the resulting bimetallic 3D-PdCu electrode exhibits enhanced capabilities by energy conversion related reactions -hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR)- when compared with the monometallic 3D-Cu counterpart. Thus, this simple functionalization approach provides a custom way for manufacturing functional metal-based 3D-printed electronics harboring noble metal catalysts to improve energy-converting applications on-demand and beyond.
查看更多>>摘要：Photocatalytic degradation of indoor VOCs has great prospects for addressing human health issues in daily life. Here, TiO2 containing fluorine ions (F~-) on the surface was reduced by hydrogen to obtain the oxygen vacancy-rich sample F-TiO_(2-x). which exhibited excellent performance in the photocatalytic VOCs degradation. The characterization results showed that the strong electron repulsion between F~- and Ti~(3+) encouraged metallization to promote photogenerated charges separation. The DFT calculation results proved that the F~- on the surface of TiO2 was beneficial to the formation of surface oxygen vacancies, and the synergistic effect of oxygen vacancies and F~- on F-TiO_(2-x) could improve the adsorption and activation of H2O molecules, which was also effective for oxygen molecules. All of these were beneficial to the formation of active free radicals. Moreover, the presence of surface F~- could effectively promote the stabilization of oxygen vacancies.
查看更多>>摘要：Polymeric carbon nitride (PCN) has great potential for peroxydisulfate (PDS) activation but still challenge due to the sluggish electron-hole pair dissociation and tardy charge transfer dynamics. Herein, a novel PCN-based donor-acceptor conjugated polymer (PCN/4-MI D-A) is synthesized by copolymerization of urea and 4-methoxyphenyl isothiocyanate. The obtained PCN/4-MI D-A exhibited significantly improved activity on PDS activation for nitenpyram (NTP) degradation under visible light. As a result, PDS+PCN/4-MI_(75) shows the highest kinetic constants (0.115 min~(-1)), which is ～6.8 times as that of the pure PCN. Density functional theory (DFT) calculations indicated that 4-methoxyphenyl as an electron-donating group promotes the charge separation/transfer of PCN/4-MI D-A. In addition, the PCN/4-MI D-A is more conducive to the PDS adsorption at the position where the amino group linked with 4-MI. The PCN/4-MI D-A generated abundant electrons which were subsequently transferred to the PDS by tunneling effect. This study provides a new design concept for the highly efficient PDS activation by constructed PCN-based donor-acceptor conjugated polymers.
查看更多>>摘要：g-C3N4 is an appealing non-metal photoeatalyst for CO2 reduction, while it shows unsatisfactory performance due to poor CO2 adsorption ability and deficient collection of photo-excited charges, but its efficiency greatly relies on the effective bulk and surface separation of photoexcited charge carriers. To address the challenges, we elaborately design Ag nanoparticles decorated 3D ordered g-C3N4 assemblies based on a synergistic route of Ag-induced supramolecular tailoring and assembling followed by thermal polymerization. The 3D structural topology of the nano-units for g-C3N4 can be altered from 2D orderly stacked nanosheets to 1D twisty g-C3N4 nanotubes by varying the amount of Ag(I). Moreover, the band structures and nitrogen vacancies can also be well-regulated. As supported by experimental and DFT calculation results, ACNNT-2 demonstrates excellent CO2 adsorption capacity, superior light harvesting ability, efficient charge separation and more localized charge density distribution, which can effectively decrease the energy barrier for COOH~* intermediate and boost the CO~* desorption, resulting in a superior photocatalytic selectivity. Consequently, in sharp contrast to BCN, the ACNNT-2 manifests a markedly improved CO generation rate of 145.5 μmol g~(-1)h~(-1) under visible-light irradiation, reflecting an 18-fold enhancement together with a CO selectivity of 89%. This strategy provides a profound insight into the multiscale modulation of g-C3N4 photocatalysts with enhanced efficiency.
查看更多>>摘要：Co-applying facet and defect engineering on SrTiO3 is critical to enhance the photocatalytic activity, and the Sr~(2+) vacancies contribute to the greater modulation capacity in A-site for designing defect engineering. Here, we use advanced characterizations combined with density functional theory to elucidate the origin of K-modulated facet and defect in SrTiO3 nanoparticles, thereby affecting the photocatalytic activities in overall water splitting. We found that the differences in binding strength between K2CO3 and different facets led to the exposure of non-equivalent facets. Based on the facet engineering, we demonstrated that the K-doping process consisted of filling and substitution process, and the lowest defect concentration existed at their intersection and with a maximum bending degree of surface energy band between {100} and {110} facets. The optimized 3%K-doped SrTiO3 composites have an intrinsic activity comparable to state-of-the-art catalysts. This work provides a significant theoretical guidance for rationally designing the high-performance SrTiO3-based photocatalysts.
查看更多>>摘要：A composite photocatalyst of Ag2O and Na doped g-C3N4 (Ag2O/Na-CN) with high efficiency was investigated for photocatalytic oxidative desulfurization (PODS). The concentration and lifetime of carriers are increased with Na-CN. Under light conditions, it produces more charge carriers for the generation of radical species, such as superoxide radicals and holes. In addition, Na-CN and Ag2O form a p-n heterojunction, facilitating the transfer and separation of photogenerated electrons and holes, and increasing the concentration of holes on the valence band of Ag2O. The significantly improved charge separation alone with the higher carrier concentration of Ag2O/Na-CN makes the activation and oxidation of thiophene easier. Free radical capture experiments, electron paramagnetic resonance, and gas chromatography-mass spectrometry tests showed that holes, electrons, and superoxide radicals are the most critical active species in the PODS process, supporting the proposed PODS mechanism.
查看更多>>摘要：Owing to the large bandgap and inappropriate surface absorption energy, few reports can achieve commercially valuable carbon products, especially alkanes, through CO2 photoreduction. Herein, a new narrow band-gapped perovskite oxysulfide, Ba2Bi_(1+x)Ta_(1-x)O_(6-y)S_y, is developed for CO2 photoreduction to produce ethane. It enhances the charge separation, facilitates the charge transfer, and reduces the reaction energy to ~*CH3, promoting phtotocatalytic CO2 reduction towards C2H6. The obtained perovskite oxysulfide has a C2H6 yield of over 5.4 μmol g~(-1) h~(-1) with the yield-based selectivity of 30.2% and the electron-based selectivity of 65.6%. It also has outstanding stability for both photocatalytic water oxidation and CO2 reduction. The novel design and construction of a photocatalyst in this work could open new possibility for the practical application of artificial photosynthesis.
查看更多>>摘要：Photoelectrochemical (PEC) CO2 reduction is regarded as an intriguing but severely impeded by poor selectivity of C2 products in aqueous solution. Here, we constructed a hybrid catalyst consisting of active Cu-N sites decorated CuO (CuN_x/CuO) for PEC CO2 reduction. The CuN_x/CuO photocathode delivers photocurrent density of -1.0 mA/cm~2 at 0.2 V vs. RHE, increasing to 2.5 folds of CuO. The hybrid photocathode presents Faradaic efficiencies toward C2 products of 15.2 % at 0.2 V vs. RHE in aqueous solution. Theoretical calculations demonstrate that Cu-N pair with asymmetric d-p orbital anchored on CuO can significantly reduce C-C coupling free energy, stemming from tuned binding strength of intermediates. This makes the OCCO~* and ~*COCH2 intermediates toward C2 products adsorption on Cu-N site easier than that on Cu-Cu site. Besides, the local charge re-distribution induced by Cu-N pair enhances conductivity, giving rise to increased photocurrent density and high electron migration efficiency.
查看更多>>摘要：Electro-Fenton (EF) is a promising electrochemical technology in degrading recalcitrant organic pollutants. However, the technology faces problems of high energy consumption, low cathodic oxygen transfer rate and low H2O2 production efficiency. Therefore, a novel air-breathing gas diffusion electrode (GDE) with multiform hydrophobic layers was prepared by a facile method. The novel GDE allows the air to diffuse to the triphase interface spontaneously, eliminating the cost of aeration. Also, the multiform hydrophobic layers can greatly improve the oxygen transfer rate and expand the triphase interfaces in the GDE, resulting in a high H2O2 accumulation of 44.30 mg L~(-1) cm~(-2) h~(-1) without aeration, which was 18 times higher than that of the virgin cathode. A 100% degradation efficiency of sulfadiazine (SDZ) was achieved with the fabricated GDE in 10 min in EF system. Moreover, theoretical calculations were performed for accurately elucidating the SDZ degradation mechanism and pathway.
查看更多>>摘要：In this work, carbon nanotubes with fluorine-rich surface are firstly developed as advanced metal-free catalysts for the electrocatalytic synthesis of urea via co-activation of CO2 and NO3 under ambient conditions. A high yield rate of 6.36 mmol h~(-1) g_(cat.)~(-1) with a corresponding Faradaic efficiency of 18.0% was achieved for the urea formation at - 0.65 V vs. reversible hydrogen electrode. Density functional theory calculations indicate the formation of ~*CO and ~*NH2 intermediates is favorable on F-doped C active sites ('C-F2' moieties), facilitating the C-N coupling reaction to form urea.
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