2D MXene-derived Nb2O5/C/Nb2C/g-C3N4 heterojunctions for efficient nitrogen photofixation,Catalysis Science & Technology

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2D MXene-derived Nb2O5/C/Nb2C/g-C3N4 heterojunctions for efficient nitrogen photofixation
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2020-07-15 , DOI: 10.1039/d0cy00656d
Heyan Jiang _{1,

2,

3,

4,

5} , Cuicui Zang _{1,

2,

3,

4,

5} , Yinglan Zhang _{1,

2,

3,

4,

5} , Wenhai Wang _{6,

7,

8,

9} , Chaofen Yang _{9,

10,

11,

12} , Bin Sun _{1,

2,

3,

4,

5} , Yu Shen _{1,

2,

3,

4,

5} , Fengxia Bian _{1,

2,

3,

4,

5}

Affiliation

Due to the rather high 940.95 kJ mol⁻¹ thermodynamic cleavage energy of the N–N triple bond, developing a robust catalytic process for N₂ reduction under mild conditions is a continuing scientific challenge. Here, 2D MXene-derived niobium pentoxide/carbon/niobium carbide/graphite-like carbon nitride (Nb₂O₅/C/Nb₂C/g-C₃N₄) heterojunctions were explored as photocatalysts for N₂ reduction in water. Nb₂O₅/C/Nb₂C/g-C₃N₄ heterojunctions were prepared by uniformly growing Nb₂O₅ on Nb₂C and then forming g-C₃N₄ nanosheets in situ on Nb₂O₅/C/Nb₂C. With an optimized Nb₂O₅/C/Nb₂C : g-C₃N₄ ratio of 1 : 1, Nb₂O₅/C/Nb₂C/g-C₃N₄ showed a high nitrogen reduction rate (0.365 mmol h⁻¹ g_cat⁻¹), which was 9.1 times as high as that of the MXene derived Nb₂O₅/g-C₃N₄ composite. It is worth mentioning that the enhanced performance of Nb₂O₅/C/Nb₂C/g-C₃N₄ should be attributed to the enhancement in photogenerated electron and hole separation efficiency caused by the short-range directional charge transmission over the close contact between Nb₂O₅ and conductive Nb₂C as well as the Schottky junction formed at the Nb₂O₅/Nb₂C interface. By further changing the pH of the catalytic system, the concentration of reactive electrons was adjusted and the energy barrier of proton reduction was improved. With the optimized pH of 9 adjusted with NaOH solution, the nitrogen reduction efficiency could be further promoted 2.5 times (0.927 mmol h⁻¹ g_cat⁻¹).

中文翻译：

二维MXene衍生的Nb2O5 / C / Nb2C / g-C3N4异质结，可实现高效的氮光固定

由于N-N三键的相当高的940.95 kJ mol ^-1热力学裂解能，在温和条件下开发出可靠的N ₂还原催化方法一直是科学上的挑战。在此，探索了2D MXene衍生的五氧化二铌/碳/碳化铌/石墨状氮化碳（Nb ₂ O ₅ / C / Nb ₂ C / gC ₃ N ₄）异质结作为光催化剂，用于还原水中的N ₂。通过均匀生长Nb ₂ O制备Nb ₂ O ₅ / C / Nb ₂ C / gC ₃ N ₄异质结₅在Nb₂ C上，然后在Nb₂ O₅ / C / Nb₂ C上原位形成gC₃ N₄纳米片。优化的Nb₂ O₅ / C / Nb₂ C：gC₃ N₄比例为1：1 Nb₂ O₅ / C / Nb₂ C / gC₃ N₄的氮还原率高（0.365 mmol h^-1 g_cat^-1），是MXene衍生的Nb₂ O_5的9.1倍/GC₃ N₄复合材料。值得一提的是，Nb₂ O₅ / C / Nb₂ C / gC₃ N₄的性能增强应归因于近距离接触引起的短程定向电荷传输导致光生电子和空穴分离效率的提高。 Nb₂ O₅和导电Nb₂ C之间的介电常数以及在Nb₂ O₅ / Nb₂处形成的肖特基结C接口。通过进一步改变催化体系的pH，调节了反应性电子的浓度，并改善了质子还原的能垒。通过用NaOH溶液调节的最适pH为9，氮还原效率可以进一步提高2.5倍（0.927 mmol h ^-1 g _cat^-1）。

更新日期：2020-09-05

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