Unveiling the dominant distal-alternating hybrid mechanism in B-modulated Mo2TiC2Tx/MoO2 MXene for highly selective ambient NRR

doi:10.1016/S1872-2067(26)65080-2

Abstract

Abstract:

Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions offers a sustainable alternative to the energy-intensive Haber-Bosch process. However, the two canonical catalytic pathways face intrinsic limitations: the alternating mechanism suffers from high *NH₂NH₂ desorption losses, while the distal pathway requires prohibitive activation energy for N₂ protonation. The simultaneous realization of high activity and selectivity thus remains a critical challenge. Here, we demonstrate that boron doping modulates the electronic structure of Mo₂TiC₂T_x/MoO₂ by upshifting the d-/p-band center toward the Fermi level, unveiling the dominant a hybrid “distal-alternating” pathway that favors the *NNHH → *NHNH₂ transition rather than the *NNHH → *N cleavage. In addition, the electron-deficient B sites weaken the binding affinity toward Lewis-acidic protons under acidic conditions, thereby effectively suppressing the competing hydrogen evolution reaction. Significant interfacial charge transfer from MoO₂ to the B@Mo₂TiC₂T_x surface further ensures a sufficient electron supply for N₂ activation and stepwise hydrogenation. As a result, B@Mo₂TiC₂T_x/MoO₂ delivers an impressive ammonia yield of 121.18 μg h^‒1 mg_cat.^‒1 with a Faradaic efficiency of 75.94% at a mild potential of -0.2 V vs. RHE. This work unveils the mechanistic feasibility of a non-classical hybrid NRR pathway and establishes a rational strategy for designing next-generation high-efficiency nitrogen reduction electrocatalysts.

Key words: B@Mo₂TiC₂T_x/MoO₂ electrocatalyst, Nitrogen reduction reaction, Hybrid distal-alternating mechanism, Electron band engineering, Ambient ammonia synthesis

Fengjuan Guo, Chunyao Ma, Yue Huang, Sitong Hang, Junwei Ma, Hongtao Gao. Unveiling the dominant distal-alternating hybrid mechanism in B-modulated Mo₂TiC₂T_x/MoO₂ MXene for highly selective ambient NRR[J]. Chinese Journal of Catalysis, 2026, 87: 269-281.

×
share this article

Add to citation manager EndNote|Ris|BibTeX

URL: https://www.cjcatal.com/EN/10.1016/S1872-2067(26)65080-2

https://www.cjcatal.com/EN/Y2026/V87/I8/269

Figures/Tables 7

Fig. 1. (a) Schematic depiction of the mechanism for N2 reduction to NH3. (b) Schematic diagram of the synthesis process for B@Mo2TiC2Tx/MoO2 MXene. (c) XRD patterns of the Mo2TiC2Tx/MoO2 and B@Mo2TiC2Tx/MoO2. The SEM (d) and HRTEM (e) images of B@Mo2TiC2Tx/MoO2 MXene. (f) Elemental mapping images of Mo, Ti, C, B, and O in B@Mo2TiC2Tx/MoO2 MXene composites.

Fig. 2. Mo 3d (a), Ti 2p (b), and O 1s (c) XPS spectra of B@Mo2TiC2Tx/MoO2 and Mo2TiC2Tx MXene. (d) The B 1s XPS spectrum of B@Mo2TiC2Tx/MoO2 MXene composites.

Fig. 3. (a) Ammonia yield and Faradaic efficiency of B@Mo2TiC2Tx/MoO2 at different potentials. (b) Cyclic stability and (c) Time-dependent current density of B@Mo2TiC2Tx/MoO2 at -0.2 V vs. Ag/AgCl. The ECSA (d), Nyquist plot (e) of B@Mo2TiC2Tx/MoO2 and Mo2TiC2Tx/MoO2 catalysts, and UV-Vis absorbance spectra (f) of B@Mo2TiC2Tx/MoO2 under various control conditions. (g) 1H NMR spectra of the electrolyte after NRR at -0.2 V using 15N2- and 14N2-saturated aliquots of 0.1 mol L?1 H2SO4 as the nitrogen sources. (h) Comparison of the results of this work with state-of-the-art electrocatalytic NRR catalysts in terms of yield rate and FE.

Fig. 4. The charge density difference of the B@Mo2TiC2Tx/MoO2 heterojunction (a) and the N2 molecule adsorbed on B@Mo2TiC2Tx/MoO2 MXene catalyst (b). (c) The PDOS of B@Mo2TiC2Tx/MoO2 MXene. The charge accumulation and depletion were depicted by yellow and green, respectively, and the isosurface value is 0.004 e Å?3.

Fig. 5. (a) Orbital compositions of the N2. (b) The electron “donation/back-donation” mechanism between N2 and the B atom. (c) The PDOS of free N2 and its adsorption on B@Mo2TiC2Tx/MoO2 MXene. (d) The COHP of free N2 and N2 adsorbed on B@Mo2TiC2Tx/MoO2 MXene.

Fig. 6. (a) In-situ FTIR spectra of B@Mo2TiC2Tx/MoO2 MXene. (b) Free energy profiles for NRR on B@Mo2TiC2Tx/MoO2. (c) Atomic configurations along the distal-alternating mechanism. (d) Free energy profiles for NRR on Mo2TiC2Tx/MoO2.

Fig. 7. (a) The Gibbs free energy profiles for HER on Mo2TiC2Tx/MoO2 and B@Mo2TiC2Tx/MoO2. (b) The adsorption Gibbs free energy of *H and *N2 on Mo2TiC2Tx/MoO2 and B@Mo2TiC2Tx/MoO2. (c) The plot of UL(NH3) versus UL(NH3) - UL(HER) for Mo2TiC2Tx/MoO2 and B@Mo2TiC2Tx/MoO2.

References

[1]	Y. Guo, T. Wang, Q. Yang, X. Li, H. Li, Y. Wang, T. Jiao, Z. Huang, B. Dong, W. Zhang, J. Fan, C. Zhi, ACS Nano, 2020, 14, 9089-9097.
[2]	Y. Sun, Y. Han, X. Zhang, W. Cai, Y. Zhang, Y. Zhang, Z. Li, B. Li, J. Lai, L. Wang, Appl. Catal. B, 2022, 319, 121933.
[3]	X. Wang, R. Zhang, C. Ma, W. Yan, Y. Wei, J. Tian, M. Ma, Q. Li, M. Shao, J. Energy Chem., 2023, 87, 439-449.
[4]	D. K. D. Chittibabu, N. Sathishkumar, S.-Y. Wu, H.-T. Chen, ACS Appl. Energy Mater., 2023, 6, 6636-6645.
[5]	A. Das, S. Das, B. Pathak, Chem. Asian J., 2023, 18, e202300075.
[6]	J.-N. Hu, L.-C. Tian, H. Wang, Y. Meng, J.-X. Liang, C. Zhu, J. Li, Chin. J. Catal., 2023, 52, 252-262.
[7]	S. Murmu, S. Paul, S. Kapse, R. Thapa, S. Chattopadhyay, N. Abharana, S. N. Jha, D. Bhattacharyya, U. K. Ghorai, J. Mater. Chem. A, 2021, 9, 14477-14484.
[8]	Y. Zhao, J. Xu, Z. Huang, Y. Wang, Y. Li, H. Wei, ACS Appl. Mater. Interfaces, 2025, 17, 12156-12168.
[9]	X. Chen, G. Ren, Y. Wang, Z. Li, Z. Zhang, X. Meng, Appl. Catal. B, 2024, 355, 124173.
[10]	Y. Wan, M. Zheng, R. Lv, Mater. Today Energy, 2023, 32, 101240.
[11]	J. Xia, S.-Z. Yang, B. Wang, P. Wu, I. Popovs, H. Li, S. Irle, S. Dai, H. Zhu, Nano Energy, 2020, 72, 104681.
[12]	A. Adalder, K. Mitra, S. Bhowmick, U. K. Ghorai, Adv. Energy Mater., 2025, e05111.
[13]	Y. Wang, M. Batmunkh, H. Mao, H. Li, B. Jia, S. Wu, D. Liu, X. Song, Y. Sun, T. Ma, Chin. Chem. Lett., 2022, 33, 394-398.
[14]	X. Chen, S. Zhang, X. Qian, Z. Liang, Y. Xue, X. Zhang, J. Tian, Y. Han, M. Shao, Appl. Catal. B, 2022, 310, 121277.
[15]	S. Sarkar, N. Mukherjee, S. J. Alli, P. Bhabak, A. Adalder, S. Mukherjee, R. Thapa, U. K. Ghorai, ACS Appl. Energy Mater., 2024, 7, 11094-11102.
[16]	C. Wang, Q.-C. Wang, K.-X. Wang, M. De Ras, K. Chu, L.-L. Gu, F. Lai, S.-Y. Qiu, H. Guo, P.-J. Zuo, J. Hofkens, X.-D. Zhu, J. Energy Chem., 2023, 77, 469-478.
[17]	G. Yang, H. Zhang, J. Li, Y. Wang, K. Deng, H. Yu, H. Wang, Z. Wang, L. Wang, ACS Appl. Nano Mater., 2024, 7, 10895-10901.
[18]	S. Paul, A. Gain, A. Adalder, S. Pal, S. H. Mushrif, U. K. Ghorai, Small, 2025, 21, 2505121.
[19]	H. Sun, S. Lu, Y. Qi, J. Wu, T. Liu, J.-S. Qin, H. Rao, Adv. Sci., 2025, 12, e09323.
[20]	J. Come, M. Naguib, P. Rozier, M. W. Barsoum, Y. Gogotsi, P.-L. Taberna, M. Morcrette, P. Simon, J. Electrochem. Soc., 2012, 159, A1368-A1373.
[21]	C.-K. Tang, X. Zheng, X.-L. Chen, Y.-G. Fu, Q.-F. Lü FlatChem, 2023, 42, 100581.
[22]	R. Feng, H. Yin, L. Tian, H. Zhang, J. Zhang, J. Liu, A. Du, W. Yang, Z. Liu, Energy Fuels, 2024, 38, 11815-11823.
[23]	X. Qian, C. Ma, U. B. Shahid, M. Sun, X. Zhang, J. Tian, M. Shao, ACS Catal., 2022, 12, 6385-6393.
[24]	Y. Cheng, X. Li, P. Shen, Y. Guo, K. Chu, Energy Environ. Mater., 2023, 6, e12268.
[25]	Y. Fan, X. Hao, N. Yi, Z. Jin, Appl. Catal. B, 2024, 357, 124313.
[26]	H. He, H.-M. Wen, H.-K. Li, P. Li, J. Wang, Y. Yang, C.-P. Li, Z. Zhang, M. Du, Adv. Sci., 2023, 10, 2206933.
[27]	F. Guo, J. Ma, X. Deng, H. Gao, Fuel, 2025, 382, 133704.
[28]	Y. Zhu, G. Xu, W. Song, Y. Zhao, Z. He, Z. Miao, Ceram. Int., 2021, 47, 30005-30011.
[29]	Y. Gao, Y. Cao, H. Zhuo, X. Sun, Y. Gu, G. Zhuang, S. Deng, X. Zhong, Z. Wei, X. Li, J.-G. Wang, Catal. Today, 2020, 339, 120-126.
[30]	A. Liu, X. Liang, X. Ren, W. Guan, M. Gao, Y. Yang, Q. Yang, L. Gao, Y. Li, T. Ma, Adv. Funct. Mater., 2020, 30, 2003437.
[31]	X. Ren, J. Zhao, Q. Wei, Y. Ma, H. Guo, Q. Liu, Y. Wang, G. Cui, A. M. Asiri, B. Li, B. Tang, X. Sun, ACS Cent. Sci., 2019, 5, 116-121.
[32]	G. Li, B. Zhou, P. Wang, M. He, Z. Fang, X. Yuan, W. Wang, X. Sun, Z. Li, Catalysts, 2022, 12, 850.
[33]	Y. S. Park, A. Chae, G. H. Choi, S. Ram, S.-C. Lee, S. Bhattacharjee, J. Jung, H. S. Jeon, C.-H. Ahn, S. S. Hwang, D.-Y. Koh, I. In, T. Oh, S. J. Kim, C. M. Koo, A. S. Lee, Appl. Catal. B, 2024, 346, 123731.
[34]	H. Kim, B. Anasori, Y. Gogotsi, H. N. Alshareef, Chem. Mater., 2017, 29, 6472-6479.
[35]	X. Qian, Y. Wei, M. Sun, Y. Han, X. Zhang, J. Tian, M. Shao, Chin. J. Catal., 2022, 43, 1937-1944.
[36]	C. Cao, J. Li, L. Zhang, Y. Hu, L. Zhang, W. Yang, J. Mater. Sci. Technol., 2025, 214, 180-193.
[37]	S. Paul, S. Sarkar, D. Dolui, D. Sarkar, M. Robert, U. K. Ghorai, Dalton Trans., 2023, 52, 15360-15364.
[38]	N. Venkateswara Rao Nulakani, V. Surya Kumar Choutipalli, M. Akbar Ali, Appl. Surf. Sci., 2025, 680, 161470.
[40]	C. Liu, H. Zheng, T. Wang, Z. Guo, F. Zhu, H. Xie, G. Qin, H. Li, S. Li, J. Mater. Sci. Technol., 2023, 159, 244-250.
[41]	W. Zhou, H. Shen, H. Xie, Y. Shen, W. Kang, Q. Wang, Y. Kawazoe, P. Jena, J. Phys. Chem. Lett., 2021, 12, 12142-12149.
[42]	Z. Wen, H. Lv, X. Wu, ACS Appl. Mater. Interfaces, 2022, 14, 52079-52086.
[43]	C. Liu, T. Wang, D. Hao, Q. Li, S. Li, C. Sun, J. Mater. Sci. Technol., 2022, 110, 96-102.
[44]	X. Liu, Y. Jiao, Y. Zheng, S.-Z. Qiao, ACS Catal., 2020, 10, 1847-1854.
[45]	Q. Li, C. Liu, S. Qiu, F. Zhou, L. He, X. Zhang, C. Sun, J. Mater. Chem. A, 2019, 7, 21507-21513.
[46]	S. Zhou, X. Yang, X. Xu, S.-X. Dou, Y. Du, J. Zhao, J. Am. Chem. Soc., 2020, 142, 308-317.
[47]	X. Feng, J. Liu, L. Chen, Y. Kong, Z. Zhang, Z. Zhang, D. Wang, W. Liu, S. Li, L. Tong, J. Zhang, J. Am. Chem. Soc., 2023, 145, 10259-10267.
[48]	Y. Sun, X. Li, Z. Wang, L. Jiang, B. Mei, W. Fan, J. Wang, J. Zhu, J.-M. Lee, J. Am. Chem. Soc., 2024, 146, 7752-7762.
[49]	T. M. Buscagan, D. C. Rees, Joule, 2019, 3, 2662-2678.
[50]	C. Zhang, Q. Wang, Z. Li, H. Liu, L. Zhong, J. Liu, Z. Wang, R. Wu, P. Song, W.-J. Chen, Z. Qi, C. Yan, L. Song, Q. Yan, C. Lv, Angew. Chem. Int. Ed., 2025, 64, e202502957.
[51]	L. Tao, K. Pang, W. Qin, L. Huang, L. Duan, G. Zhu, Q. Li, C. Yu, Catal. Sci. Technol., 2023, 13, 4517-4524.
[52]	X. Luo, Y. Wu, H. Hu, T. Wei, B. Wu, J. Ding, Q. Liu, J. Luo, X. Liu, Small, 2024, 20, 2403399.
[53]	H. Zhang, Y. Huang, X. Wang, J. Meng, L. Gao, Y. Li, Y. Zhang, Y. Liao, W.-L. Dai, Sep. Purif. Technol., 2025, 360, 131199.
[54]	Q. Zhao, W. Zhou, M. Zhang, Y. Wang, Z. Duan, C. Tan, B. Liu, F. Ouyang, Z. Yuan, H. Tai, Y. Jiang, Adv. Funct. Mater., 2022, 32, 2270220.
[55]	J. Halim, K. M. Cook, P. Eklund, J. Rosen, M. W. Barsoum, Appl. Surf. Sci., 2019, 494, 1138-1147.
[56]	N. Han, W. Guo, L. Fan, Y. Yan, B. Weng, J. E. Huang, J. Wu, P.-Y. Tang, Y. Bai, Y.-M. Zheng, S. Wang, X. Zhang, B.-L. Su, Adv. Mater., 2025, 37, e00900.
[57]	T. Wu, Y. Du, Z.-J. Zuo, S. Li, J. Wu, J. Gao, T. Mu, Y.-C. Zhang, X.-D. Zhu, Adv. Funct. Mater., 2025, 35, 2424142.
[58]	P. Li, Z. Zhou, Q. Wang, M. Guo, S. Chen, J. Low, R. Long, W. Liu, P. Ding, Y. Wu, Y. Xiong, J. Am. Chem. Soc., 2020, 142, 12430-12439.
[59]	H. Xiao, M. Xia, B. Chong, H. Li, B. Lin, G. Yang, Appl. Catal. B, 2024, 343, 123474.
[60]	R. Liu, Q. Chen, J. Qiu, C. Liu, J. Wu, J. C. Yu, L. Wu, J. Colloid Interface Sci., 2025, 692, 137504.
[61]	Y. Zhang, L. Ran, Y. Zhang, P. Zhai, Y. Wu, J. Gao, Z. Li, B. Zhang, C. Wang, Z. Fan, X. Zhang, J. Cao, D. Jin, L. Sun, J. Hou, ACS Nano, 2021, 15, 17820-17830.
[62]	H. Wang, C. Zhang, B. Liu, W. Li, C. Jiang, Z. Ke, D. He, X. Xiao, Adv. Mater., 2024, 36, 2401032.
[63]	Z. Zhao, Y. Nian, J. Shi, X. Xin, X. Huang, Y. Shi, J. Tan, Y. Zhang, Y. Han, D. Yang, Z. Jiang, ACS Catal., 2024, 14, 11626-11634.

Unveiling the dominant distal-alternating hybrid mechanism in B-modulated Mo₂TiC₂T_x/MoO₂ MXene for highly selective ambient NRR

RichHTML

PDF (PC)

Knowledge

Supporting Information

Abstract

Cite this article

share this article

share this article

Figures/Tables 7

References

Related Articles 15

Recommended Articles

Metrics

[1]	Dezhi Wang, Songhua Yang, Yiyi Yangliu, Xufa Peng, Fangyang Liu, Hao Fei, Zhuangzhi Wu. Decoupling competitive reactions by their differential orbital-coupling response to vacancy engineering for efficient electrocatalytic nitrogen reduction [J]. Chinese Journal of Catalysis, 2026, 86(7): 181-190.
[2]	Liyuan Xiao, Zhenlu Wang, Jingqi Guan. Advances in multinuclear metal-organic frameworks for electrocatalysis [J]. Chinese Journal of Catalysis, 2026, 80(1): 59-91.
[3]	Nan Mu, Tingting Bo, Yugao Hu, Ruixin Xu, Yanyu Liu, Wei Zhou. Single-atom catalysts based on polarization switching of ferroelectric In₂Se₃ for N₂ reduction [J]. Chinese Journal of Catalysis, 2024, 63(8): 244-257.
[4]	Guangtong Hai, Zhongheng Fu, Xin Liu, Xiubing Huang. Recent progress in electrocatalytic reduction of nitrogen to ammonia [J]. Chinese Journal of Catalysis, 2024, 60(5): 107-127.
[5]	Yingying Wei, Yuyao Sun, Yaodong Yu, Yue Shi, Zhe Wu, Lei Wang, Jianping Lai. 4 d Metal-doped liquid Ga for efficient ammonia electrosynthesis at wide N₂ concentrations [J]. Chinese Journal of Catalysis, 2024, 67(12): 194-203.
[6]	Siyu Chen, Jingqi Guan. Structural regulation strategies of nitrogen reduction electrocatalysts [J]. Chinese Journal of Catalysis, 2024, 66(11): 20-52.
[7]	Ziyuan Xiu, Wei Mu, Xin Zhou, Xiaojun Han. Mild polarization electric field in ultra-thin BN-Fe-graphene sandwich structure for efficient nitrogen reduction [J]. Chinese Journal of Catalysis, 2024, 65(10): 126-137.
[8]	Ji Zhang, Aimin Yu, Chenghua Sun. Theoretical insights into heteronuclear dual metals on non-metal doped graphene for nitrogen reduction reaction [J]. Chinese Journal of Catalysis, 2023, 52(9): 263-270.
[9]	Qi-Ni Zhan, Ting-Yu Shuai, Hui-Min Xu, Chen-Jin Huang, Zhi-Jie Zhang, Gao-Ren Li. Syntheses and applications of single-atom catalysts for electrochemical energy conversion reactions [J]. Chinese Journal of Catalysis, 2023, 47(4): 32-66.
[10]	Ya Li, Zhenkang Wang, Haoqing Ji, Lifang Zhang, Tao Qian, Chenglin Yan, Jianmei Lu. Excluding false positives: A perspective toward credible ammonia quantification in nitrogen reduction reaction [J]. Chinese Journal of Catalysis, 2023, 44(1): 50-66.
[11]	Wei Xiong, Min Zhou, Hao Li, Zhao Ding, Da Zhang, Yaokang Lv. Electrocatalytic ammonia synthesis catalyzed by mesoporous nickel oxide nanosheets loaded with Pt nanoparticles [J]. Chinese Journal of Catalysis, 2022, 43(5): 1371-1378.
[12]	Hui Mao, Haoran Yang, Jinchi Liu, Shuai Zhang, Daliang Liu, Qiong Wu, Wenping Sun, Xi-Ming Song, Tianyi Ma. Improved nitrogen reduction electroactivity by unique MoS₂-SnS₂ heterogeneous nanoplates supported on poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide [J]. Chinese Journal of Catalysis, 2022, 43(5): 1341-1350.
[13]	Ziyi Jiang, Youcheng Hu, Jun Huang, ShengLi Chen. A combinatorial descriptor for volcano relationships of electrochemical nitrogen reduction reaction [J]. Chinese Journal of Catalysis, 2022, 43(11): 2881-2888.
[14]	Kai S. Exner. Beyond the thermodynamic volcano picture in the nitrogen reduction reaction over transition-metal oxides: Implications for materials screening [J]. Chinese Journal of Catalysis, 2022, 43(11): 2871-2880.
[15]	Bin Huang, Yifan Wu, Bibo Chen, Yong Qian, Naigen Zhou, Neng Li. Transition-metal-atom-pairs deposited on g-CN monolayer for nitrogen reduction reaction: Density functional theory calculations [J]. Chinese Journal of Catalysis, 2021, 42(7): 1160-1167.