As a metal‐free nitrogen reduction reaction (NRR) photocatalyst, g‐C3N4 is available from a scalable synthesis at low cost. Importantly, it can be readily functionalized to enhance photocatalytic ...activities. However, the use of g‐C3N4‐based photocatalysts for the NRR has been questioned because of the elusive mechanism and the involvement of N defects. This work reports the synthesis of a g‐C3N4 photocatalyst modified with cyano groups and intercalated K+ (mCNN), possessing extended visible‐light harvesting capacity and superior photocatalytic NRR activity (NH3 yield: 3.42 mmol g−1 h−1). Experimental and theoretical studies suggest that the ‐C≡N in mCNN can be regenerated through a pathway analogous to Mars van Krevelen process with the aid of the intercalated K+. The results confirm that the regeneration of the cyano group not only enhances photocatalytic activity and sustains the catalytic cycle, but also stabilizes the photocatalyst.
Active site: A superior g‐C3N4 photocatalyst for the nitrogen reduction reaction (NRR) is reported. The catalyst features ‐C≡N groups and intercalated K+, and is used as model to investigate the mechanistic pathway of the photocatalytic NRR involving ‐C≡N‐type active sites.
It is an important issue that exposed active nitrogen atoms (e.g., edge or amino N atoms) in graphitic carbon nitride (g‐C3N4) could participate in ammonia (NH3) synthesis during the photocatalytic ...nitrogen reduction reaction (NRR). Herein, the experimental results in this work demonstrate that the exposed active N atoms in g‐C3N4 nanosheets can indeed be hydrogenated and contribute to NH3 synthesis during the visible‐light photocatalytic NRR. However, these exposed N atoms can be firmly stabilized through forming BNC coordination by means of B‐doping in g‐C3N4 nanosheets (BCN) with a B‐doping content of 13.8 wt%. Moreover, the formed BNC coordination in g‐C3N4 not only effectively enhances the visible‐light harvesting and suppresses the recombination of photogenerated carriers in g‐C3N4, but also acts as the catalytic active site for N2 adsorption, activation, and hydrogenation. Consequently, the as‐synthesized BCN exhibits high visible‐light‐driven photocatalytic NRR activity, affording an NH3 yield rate of 313.9 µmol g−1 h−1, nearly 10 times of that for pristine g‐C3N4. This work would be helpful for designing and developing high‐efficiency metal‐free NRR catalysts for visible‐light‐driven photocatalytic NH3 synthesis.
The BNC coordination formed by boron doping in g‐C3N4 nanosheets is the catalytic active site for the high‐efficiency photocatalytic nitrogen reduction reaction. It also effectively immobilizes the exposed active N atoms of g‐C3N4, inhibits the recombination of photogenerated charges, and improves the visible‐light harvesting efficiency.
Co/CoO nanoparticles immobilized on Co-N-doped carbon were successfully developed using shrimp-shell derived N-doped carbon nanodots as precursors by a combined approach of polymerization and ...pyrolysis, as electrocatalysts exhibiting trifunctional catalytic activities toward oxygen reduction, oxygen evolution and hydrogen evolution reactions and high performance in rechargeable zinc-air batteries.
In this work, we integrated Ag
3
PO
4
with Bi
4
Ti
3
O
12
to form Bi
4
Ti
3
O
12
/Ag
3
PO
4
heterojunction nanocomposites by an ion-exchange method. The as-prepared Bi
4
Ti
3
O
12
/Ag
3
PO
4
...composites were systematically characterized by means of XRD, SEM, TEM, BET, XPS, UV-vis DRS, EIS, PL spectroscopy, and photocurrent response. SEM, TEM, and XPS results demonstrate the creation of Bi
4
Ti
3
O
12
/Ag
3
PO
4
heterojunction with obvious interfacial interaction between Bi
4
Ti
3
O
12
and Ag
3
PO
4
. PL spectra, EIS spectra, and photocurrent responses reveal that the composites display an enhanced separation efficiency of photogenerated electron-hole pairs, which is due to the charge transfer between Bi
4
Ti
3
O
12
and Ag
3
PO
4
. Rhodamine B (RhB) was chosen as the target organic pollutant to evaluate its degradation behavior over Bi
4
Ti
3
O
12
/Ag
3
PO
4
composites under simulated sunlight irradiation. Compared to bare Bi
4
Ti
3
O
12
and Ag
3
PO
4
nanoparticles, the composites exhibit a significantly enhanced photocatalytic activity. The highest photocatalytic activity is observed for the 10% Bi
4
Ti
3
O
12
/Ag
3
PO
4
composite with 10% Bi
4
Ti
3
O
12
content, which is about 2.6 times higher than that of bare Ag
3
PO
4
. The photocatalytic mechanism involved was investigated and discussed in detail.
In this work, we have successfully prepared sandwich-like structured N-doped porous carbon@graphene composites (N-PC@G) derived from sandwich-like structured zeolitic imidazolate framework@graphene ...oxide (ZIF-8@GO). ZIF-8@GO was obtained by in situ controllable growth of ZIF-8 nanocrystals on both surfaces of graphene oxide (GO) sheets with different contents. Experimental results demonstrate that N-PC@G-0.02 (representing GO amount of 0.02 g in reaction precursors) obtained at 900 °C possesses high surface area (1094.3 m2 g−1), bimodal-pore structure (micropores and mesopores) and high graphitization degree, exhibiting great potential as a bifunctional electrocatalyst for both ORR and OER. Compared to commercial Pt/C catalyst, the N-PC@G-0.02 shows superior electrocatalytic activity with onset and half-wave potentials of 1.01 V and 0.80 V (vs. RHE), respectively, better durability and high resistance to methanol crossover effect toward ORR in alkaline media. Also, the metal-free N-PC@G-0.02 also exhibits high electrocatalytic activity of OER, comparable to commercial RuO2 catalyst. The superior ORR and OER performance could be due to a synergistic effect between ZIF-8 derived porous carbon and graphene with regard to structure and composition of N-PC@G-0.02 with high surface area, porous structure, and suitable N doping level and type, boosting the catalytic active sites, mass transport and electron transfer.
Biohazards are widely present in wastewater, and contaminated water can arouse various waterborne diseases. Therefore, effectively removing biohazards from water is a worldwide need. In this study, a ...novel visible-light-driven (VLD) graphitic carbon nitride (g-C3N4)/TiO2 hybrid photocatalyst with high photocatalytic bacterial inactivation activity was successfully synthesized using a facile hydrothermal-calcination approach. The optimum synthesized hybrid photocatalyst is composed of micron-sized TiO2 spheres (average diameter: ca. 2 μm) and wrapped with lamellar g-C3N4 (thickness: ca. 2 nm), with narrowing bandgap (ca. 2.48 eV), leading to a significant improvement of visible light (VL) absorption and effective separation of photo-generated electron–hole pairs. This greatly enhances VL photocatalytic inactivation activity towards bacteria in water. Using this hybrid photocatalyst, 107 cfu mL−1 of Escherichia coli K-12 could be completely inactivated within 180 min under VL irradiation. SEM images indicate that bacterial cells were greatly damaged, leading to a severe leakage of intracellular components during photocatalytic inactivation processes. The study concludes that bacterial cell destruction and water disinfection can be achieved using this newly fabricated VLD hybrid photocatalyst.
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•g-C3N4/TiO2 hybrid photocatalyst was synthesized by hydrothermal-calcination method.•The visible light photocatalytic activity of catalyst was significantly enhanced.•Escherichia coli could be completely photocatalytically inactivated and destructed.•Effective separation of e−-h+ pairs lead to excellent photocatalytic activity.
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•The ultrastable 1T-MoS2 was successfully achieved via a gentle two-stage solvothermal strategy.•The formation of sulfur vacancies is critical to promote the transformation of 2H to ...1T phase.•Nearly 100 % 1T-MoS2 was obtained, and it remained highly stable in air even for 360 days.•The 1T-MoS2 showed superior sorption capacity, stability and recyclability for removal of Cr(VI).
Metallic 1T phase of MoS2 (1T-MoS2) has aroused great concern for decontamination of heavy metal ions from water. Herein, ultrastable 1T-MoS2 was successfully achieved via a gentle two-stage solvothermal strategy utilizing water and ethanol as solvent for efficient removal of Cr(VI). Notably, nearly 100 % 1T-MoS2 was obtained, and it remained highly stable in air even for 360 days. Electron paramagnetic resonance analysis showed that sulfur vacancies were in situ formed on the 1T/2H mixed phase MoS2 (M-MoS2) under the induction of ethanol, which is critical to promote the transformation of 2H to 1T phase. Molecular dynamic simulation revealed that there was strong interaction between ethanol and MoS2 surface, which could decrease the total energy of MoS2 for strengthening stability of 1T phase. Moreover, 1T-MoS2 shows superior sorption capacity (200.3 mg·g−1) for removal of Cr(VI), twice more than that of M-MoS2 and 2H phase MoS2 under the same condition. Significantly, the stable phase structure of 1T-MoS2 and chromium adsorption capacity still remained even after five cycles of chromium adsorption. The study of Cr(VI) adsorption mechanism revealed that the chromium adsorption was attributed to the undercoordinated Mo(IV) as active site and coupled with redox reaction during removal process.
Long-term high-intensity training can cause a decline in immune function in athletes. In this study, we have explored whether bovine colostrum could improve the immune function in athletes undergoing ...intensive training. Thirty professional athletes were randomly divided into control group and bovine colostrum group; both groups received one month of intensive training. The control group received usual colostrum-free diet and the bovine colostrum group was fed bovine colostrum-rich milk every day. The venous blood was collected from both groups before and after the treatment period. The results showed that the lymphocyte population increased significantly in the bovine colostrum group compared to the control group (P < 0.05). There was no significant change in CD4
+
and CD8
+
in the two groups (P < 0.05), but the CD3
+
and CD4
+
/CD8
+
of the bovine colostrum group were significantly higher than those of the control group. There were significant differences in albumin, globulin and albumin/globulin ratio in the control group (P < 0.05), but not in the bovine colostrum group after training. The bovine colostrum group had lower serum albumin and albumin/globulin (P < 0.05) and higher globulin (P < 0.05) compared to the control group. There was no significant difference in immunologic indexes before and after training in both groups (P > 0.05). The decline in the markers of immune function after high-intensity training was ameliorated by the intake of bovine colostrum.
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•N-doped activated carbon supported Ni catalyst was simply synthesized by a two-step calcination method.•N doping content and type in activated carbon have important influence on ...catalytic hydrogenation activity of Ni/NAC.•Highly active and selective H2-hydrogenation/transfer hydrogenation of furfural was studied under mild conditions.•The catalyst can be reutilized during successive catalytic cycles.•The performance enhancement mechanism has been discussed on the basis of the experimental results.
In this work, N-doped activated carbon supported metallic nickel (Ni/NAC) catalysts were fabricated by two-step calcination method in N2 atmosphere for liquid-phase hydrogenation of furfural (FAL). It was found that the pyrolysis temperature and amount of melamine as N doping source have important influence on N doping content and type in activated carbon (AC) support, resulting in the subsequently formed Ni nanoparticles on N-doped AC with different sizes and thus affording different catalytic hydrogenation activities. The results demonstrated that using N-doped AC with 1.0g melamine at 1073K in N2 atmosphere as support, the obtained Ni/NAC at 873K in N2 atmosphere with Ni nanoparticle sizes of ∼13.1nm (denoted as Ni/NAC-1-1073) exhibits a N doping content of 3.65at.% and a surface area of 561.2m2g−1 with a microporous structure. As catalyst for FAL hydrogenation, Ni/NAC-1-1073 demonstrated the best catalytic performance among all investigated catalysts, achieving almost 100% selectivity of tetrahydrofurfuryl alcohol (THFOL) with a complete FAL conversion at 353K after 3h reaction, while only 76.7% selectivity of THFOL with a FAL conversion of 86.4% was obtained using Ni/AC catalyst without N doping under the identical experimental conditions. Furthermore, it was found that almost 100% conversion of FAL to furfural alcohol (FOL) can be reached by transfer hydrogenation pathway in 2-proponal solvent using Ni/NAC-1-1073 at 413K after 5h reaction, whereas Ni/AC without N doping can only afford 30.2% conversion of FAL to FOL under the same conditions. The superior catalytic performance of Ni/NAC-1-1073 could be ascribed to a synergistic effect of nanosized Ni providing catalytic active sites, suitable N doping content and type in AC to promote catalytic performance, and advantageous structure characteristics of high surface area and porous structure favourable for the exposure of catalytic active sites and mass transport.
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