Exploiting tripeptide in Pd/C for boosting hydrogen production from formic acid dehydrogenation

Abstract

Designing highly efficient catalysts for driving the hydrogen production from formic acid (FA) dehydrogenation is of considerable practical importance for future hydrogen economies. Herein, ultrafine Pd nanoparticles (NPs) with lattice strain induced by the incorporation of tripeptide (TPT) anchored on commercial Vulcan XC-72R carbon (Pd/C-TPT) are fabricated by a facile wet-chemical process. Remarkably, the obtained Pd/C-TPT catalyst presents an extraordinary catalytic activity towards dehydrogenation of FA without any additives, giving an initial turnover frequency (TOF) value as high as 2102 mol H₂ per mol Pd per h at 323 K, which is 8.4 times than that of the Pd/C catalyst, and even much higher than most of other superior Pd catalysts reported so far. The characterization results reveal that the strain effect and size effect caused by the strong interaction between the Pd NPs and TPT tune the electronic structure of Pd for optimized formate adsorption. This study provides more flexibility for a facile and controllable synthesis strategy of efficient catalysts toward FA dehydrogenation for hydrogen production.

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1. Introduction

Hydrogen (H₂) is considered to be a promising attractive fuel with great potential as a future energy carrier owing to its high energy density and environmentally friendly characteristics.¹ Safe and efficient storage and release of H₂ are well-known technological barriers toward a fuel cell based H₂ economy.¹ Formic acid (FA, HCOOH) is a product of biomass possessing a hydrogen content of 4.4 wt%, and is nontoxic and highly stable under ordinary conditions.² Hydrogen stored in FA can be released through a dehydrogenation reaction (HCOOH → H₂(g) + CO₂(g), ΔG_{298 K} = −35.0 kJ mol⁻¹) over appropriate catalysts.³ However, FA can also undergo the dehydration reaction (HCOOH → H₂O(l) + CO(g), ΔG_{298 K} = −14.9 kJ mol⁻¹), which should be avoided because CO generated could poison the catalyst in fuel cells.³ The reaction pathway depends heavily on the catalysts. Much progress has revealed that palladium nanoparticles (NPs) are more efficient than other monometallic NPs, but their catalytic activities and selectivities are still far from desirable even with the help of additional additives (such as HCOONa or trimethylamine (NEt₃)) and elevated temperatures (333–423 K).^4,5 Thus, considerable efforts have been committed to improve the catalytic performance of Pd based catalysts by the following solutions, including the ligand effect brought by alloying and constructing core–shell structures^6,7 and the size effect through constructing a strong metal–support interaction (SMSI).^8,9 Although these solutions could effectively boost the efficiency, complicated synthetic procedures, long reaction times or extra high energy are usually unavoidable, which is very difficult and thus greatly hinders their practical applications.^10,11 In this sense, a rational and facile design of the Pd catalyst attached to commercially available carbon with excellent performance for additive-free FA dehydrogenation under ambient conditions is highly desirable.

Lattice strain, either compressive or tensile, can modulate the surface electronic structure by altering the distances between surface atoms.¹² According to the d-band theory, the d-band center can be negatively shifted by compressive strain, which can weaken the bonding of reaction intermediates to the catalyst surface, while the tensile strain is the opposite.¹³ In general, due to the bonding of Pd or Pt to intermediates being overly strong in FA dehydrogenation or the oxygen reduction reaction (ORR), previous studies have suggested that compressive strain can optimize their ability to adsorb intermediates, and thus in turn improve the catalytic activities.^14–16 In contrast, the tensile strain on the Pd and Pt surfaces is usually believed to be undesirable because such surface strain will result in overwhelming binding of the intermediates to the surfaces during the catalysis process. Recently, Guo and co-workers have demonstrated that tensile strain, which is caused by the introduction of different metals and geometric structure regulation,^17–19 can also optimize the adsorption energy and significantly improve the ORR catalytic activities. The above findings break through the previous understanding of lattice strain regulating catalytic performance, and call for further study for designing catalysts by utilizing the strain effect. Kim and co-workers have revealed that the incorporation of amino acids into calcite resulted in anisotropic lattice expansion.²⁰ Consequently, it is reasonable to deduce that the introduction of a suitable small molecule into metal catalysts may optimize electronic properties and modulate adsorption strengths through the induced strain effect, which can enhance catalytic activity at the atomic scale.

In this work, we report a facile synthesis method for the preparation of commercial Vulcan XC-72R carbon-supported ultrafine palladium NPs (Pd/C), with lattice strain in the Pd component induced by the incorporation of tripeptide (TPT). Tripeptide, a biological, green, nontoxic, and short peptide chain formed by dehydration condensation of glycine, histidine, and lysine, was chosen as a reagent because of its potential ability to form a complex interaction with the metal precursors driven by chelating with metal ions,²¹ which can be observed by UV-vis spectroscopy (Fig. 1a). Strikingly, benefiting from the strain effect and size effect caused by the strong interaction between the Pd NPs and TPT, the as-prepared Pd/C-TPT catalyst shows extraordinary catalytic activity towards dehydrogenation of FA without any additives, giving an initial turnover frequency (TOF) value as high as 2102 mol H₂ per mol catalyst per h at 323 K, which is much higher than most of other superior Pd catalysts so far reported for the heterogeneously catalyzed H₂ production from FA dehydrogenation.

Fig. 1 (a) UV-vis spectra of aqueous solutions containing TPT and metal precursor. (b) FT-IR spectrum for Pd/C-TPT. (c) XPS full spectra for (1) Pd/C-TPT and (2) Pd/C catalyst. (d) The high-resolution XPS spectrum of N 1s for the Pd/C-TPT catalyst.

2. Results and discussion

Pd/C-TPT was synthesized by the impregnation-reduction process, as schematically described in Scheme S1.† The color change is observed after blending the metallic precursors with TPT, which can be observed by UV-vis spectroscopy (Fig. 1a). To eliminate the disturbance of black carbon, only an aqueous solution of the complex precursors is used. The result suggests that the potential coordinated complex interaction between the metal precursor and TPT was driven by the chelation of the peptide with the metal ion.²¹ The subsequent facile wet-chemical process gives rise to a highly active catalyst for the dehydrogenation of FA. Fig. 1b shows the FT-IR spectrum of the Pd/C-TPT catalyst. It can be seen that the broad peak around 3416 cm⁻¹ corresponds to the –OH stretching vibration, the vibration peaks around 2938–2850 cm⁻¹ are related to the –CH₂– groups,²² bands at 1743, 1633 and 1568 cm⁻¹ are assigned to carbonyl groups, N–H stretching vibration and peptide bonds,^23–25 and the asymmetric and symmetry stretching vibrations of C–H at 1464 cm⁻¹ and 1383 cm⁻¹, respectively, confirming that TPT was successfully incorporated into Vulcan XC-72 carbon to form C-TPT in the Pd/C-TPT catalyst. To further confirm the presence of TPT in the Pd/C-TPT catalyst, XPS analyses have been taken. As shown in Fig. 1c, in addition to the peaks of Pd, C, and O, the N peak at 399.3 eV is observed for the Pd/C-TPT catalyst, whereas such N peak is absent in Pd/C NPs, further indicating that TPT has been successfully decorated into the Pd/C-TPT catalyst. To further testify the chemical state of N in Pd/C-TPT, high-resolution XPS analysis was also performed. As shown in Fig. 1d, the N 1s spectrum can be deconvoluted into two peaks with binding energies of 398.5 and 399.9 eV, which are related to pyridinic N (398.5 ± 0.2 eV) and primary amine N (399.5 ± 0.4 eV), respectively.²⁶

Fig. S1a† shows a typical TEM image of the Pd/C-TPT catalyst. It can be seen that the Pd NPs are highly dispersed on C-TPT with an average size of ∼3.8 nm. In contrast, the Pd/C prepared without TPT is agglomerated and has a larger average size of ∼9.7 nm (Fig. S1b†). It has been demonstrated that the introduction of basic amino acids is beneficial to the dehydrogenation of FA;²⁷ to understand the effect of basic amino acid-treated Pd/C in FA dehydrogenation activity, lysine and histidine, the two amino acid monomers that make up TPT, were introduced into the Pd/C catalyst for comparative study. As shown in Fig. S1c and d,† lysine treated Pd/C (Pd/C-L) and histidine treated Pd/C (Pd/C-H) show high aggregation with an average size of ∼4.8 nm, and ∼5.1 nm, respectively. The smaller particle size and the better dispersion in Pd/C-TPT suggests that TPT has abundant negatively-charged peptide nitrogen and –NH₂ groups, which are prone to adsorb Pd²⁺ through strong coordinated interactions to form initial nucleation sites, and thus C-TPT can anchor the Pd NPs without aggregation and control their sizes.

The high-resolution TEM (HRTEM) images of Pd/C-TPT and Pd/C are shown in Fig. 2a and b. Pd(111) is selected as a representative facet for researching the lattice strain. Then we examined the central regions of Pd/C-TPT and Pd/C, and obtained the average (111) facet spacing over five to six atomic layers, avoiding possible surface defects and blurry boundaries.¹⁵Fig. 2c and d are the integrated pixel intensities for the Pd(111) lattices, which are selected in Fig. 2a and b, respectively. The average Pd(111) spacings in Pd/C-TPT and Pd/C are determined to be 2.36 and 2.26 Å, respectively, which indicates that Pd(111) in Pd/C-TPT has a larger lattice spacing than that in Pd/C, implying slight tensile strain after the introduction of TPT. A further demonstration of the magnitude of lattice tensile strain was testified by aligning the upper (111) atomic layers of Pd/C-TPT and Pd/C in the Fourier transform (FFT) of the HRTEM images and observing their difference in the bottom atomic layers (Fig. 2e and f). As can be seen, the bottom layer of Pd in Pd/C-TPT is located at a much lower position than that of Pd in Pd/C, revealing the lattice tensile strain induced by TPT in Pd/C-TPT. Tensile strain also appeared in Pd/C-L and Pd/C-H (Fig. S2 and S3†) by directly comparing Pd(111) in Pd/C, with the average spacings of 2.32 Å and 2.29 Å, respectively, which strongly suggests that the incorporation of amino acids into pristine Pd/C could result in lattice expansion. The X-ray diffraction (XRD) peaks corresponding to the Pd(111) facets in Pd/C-TPT, Pd/C-L, and Pd/C-H catalysts are shifted to lower angles than that in Pd/C (Fig. 2g and S4†), respectively, demonstrating that the introduction of TPT and amino acids could induce tensile strain on Pd NPs, and this is consistent with the HRTEM result. Meanwhile, XPS valence band structures of Pd/C and Pd/C-TPT showed a narrow band width of Pd/C-TPT (Fig. 2h), which further confirms the strong interaction between Pd NPs and TPT. The metal loading for Pd/C-TPT and Pd/C is determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) to be 8.17 wt% and 8.78 wt% (Table S1†).

Fig. 2 HRTEM images of (a) Pd/C-TPT and (b) Pd/C. The integrated pixel intensities of the (c) Pd/C-TPT and (d) Pd/C catalyst along the Pd(111) spacing direction (which is perpendicular to the facets). The peaks and valleys represent the atoms and gaps, respectively. The aligned upper layers of (e) Pd/C-TPT and (f) Pd/C for the direct evidence of lattice tensile strain. The bottom atomic layer of Pd/C-TPT is located at a much lower position than that of Pd/C. Scale bar: 0.5 nm. (g) XRD spectra and (h) XPS valence bands of Pd/C-TPT and Pd/C.

The catalytic activity of the Pd/C-TPT catalyst for H₂ production from FA is investigated in a typical water-filled scale burette system and compared with Pd/C, Pd/C-L, and Pd/C-H catalysts (Fig. 3a). Remarkably, the Pd/C-TPT catalyst shows the most outstanding activity among the other catalysts, with which 225 mL of gas can be generated within 2.3 min, corresponding to a conversion of 100%. The GC result shows that the generated gas is only H₂ and CO₂ but no CO (detection limit: ≈10 ppm for CO) (Fig. S5 and S6†), indicating the complete dehydrogenation of FA into H₂ and CO₂ catalyzed by the Pd/C-TPT catalyst. In comparison, the Pd/C catalyst exhibits much lower activity (210 mL, 78 min) than Pd/C-TPT. In addition, the catalytic activities of Pd/C-L and Pd/C-H are slightly inferior to the Pd/C-TPT catalyst due to the size effect. The initial turnover frequency (TOF) (eqn (S1)†) over Pd/C-TPT is measured to be 2101.8 mol H₂ mol Pd⁻¹ h⁻¹ at 323 K, which is 8.4, 2.9, and 2.0 times higher than that of the Pd/C NPs, Pd/C-L and Pd/C-H catalysts, respectively (Fig. 3c). To the best of our knowledge, this initial TOF value is much higher than those of most superior Pd catalysts ever reported for the heterogeneously catalyzed H₂ production from FA dehydrogenation without any additive,^28–35 and even exceeds some of the values obtained with additives (Fig. 3d, Table S2†).^36–41 In order to analyze the kinetic performance of the above as-prepared catalysts, the H₂ production reactions from FA at different temperatures were performed. Fig. 3b shows that the H₂ production rate increases with the increase of the temperature. According to the Arrhenius plot, the activation energy (E_a) of the Pd/C-TPT catalyst is calculated to be 37.5 kJ mol⁻¹ (Fig. S7, eqn (S2)†), which is similar to those of Pd/C-L and Pd/C-H, lower than that of Pd/C catalysts (Fig. 3c), and comparable to most of the previously reported heterogeneous Pd monometallic catalysts for FA dehydrogenation (Fig. 3d, Table S2†).^{4,10,29,31–33,38,40,42–45} Based on the above results, Pd/C-TPT exhibits exceedingly extraordinary catalytic activity, which may benefit from the strain effect and size effect caused by the strong interaction between the Pd NPs and TPT.

Fig. 3 (a) Volume of gas generation from the dehydrogenation of FA (1.0 M, 5.0 mL) versus time at 323 K in an ambient atmosphere. (b) Arrhenius plots (ln TOF versus 1/T) and (c) the corresponding TOF and E_a values of Pd/C-TPT, Pd/C-L, Pd/C-H, and Pd/C. (d) Comparisons of catalytic activities for the dehydrogenation of FA catalyzed by previously reported heterogeneous Pd monometallic catalysts with Pd/C-TPT in this work.

To further clarify the role of the strain effect on the FA dehydrogenation activity, control experiments using PVP and CTAB mediated Pd/C have been performed. As shown in Fig. S8a and b,† although the Pd NPs supported on Pd/C-PVP and Pd/C-CTAB have similar particle sizes as those in Pd/C-L and Pd/C-H (Fig. S1†), the XRD peaks of Pd/C-PVP and Pd/C-CTAB are well corresponding to the fcc Pd(111) in Pd/C (Fig. S8c†), suggesting there is no lattice strain appeared in Pd/C-PVP and Pd/C-CTAB, which is different from Pd/C-L and Pd/C-H with tensile strain. The catalytic activities of Pd/C-PVP and Pd/C-CTAB are clearly inferior to those of Pd/C-L and Pd/C-H catalysts (Fig. S8d†), highlighting the role of the strain effect. It has been demonstrated that the presence of amine groups is facilitated to boost the dehydrogenation of FA;⁴⁶ to understand the effect of amine group-treated Pd/C in FA dehydrogenation activity, intermediates containing amine groups, such as urea and PDA treated Pd/C, were fabricated by introducing urea and PDA into Pd/C for comparative study. As shown in Fig. S9a,† Pd/C-urea and Pd/C-PDA without lattice strain (Fig. S9b†) exhibit lower catalytic activities than Pd/C-TPT, Pd/C-L and Pd/C-H, demonstrating that the enhanced catalytic activity of Pd/C-TPT, Pd/C-L and Pd/C-H can be mainly attributed to the strain effect although the effect of the amine group can more or less boost the FA dehydrogenation. To investigate the effect of C support and Pd²⁺ on the FA dehydrogenation activity, Pd-TPT and Pd²⁺/C-TPT were synthesized without introducing C and NaBH₄ for comparative study. As shown in Fig. S10,† the catalytic activity of Pd-TPT is far inferior to that of Pd/C-TPT, which indicates the dispersion effect of C support on Pd NPs. Furthermore, the Pd²⁺/C-TPT catalyst has no catalytic activity, implying Pd²⁺ can not provide catalytically active sites.

Based on the above results, it can be concluded that the strain effect originating from the strong interactions between TPT and Pd/C plays a vital role in the FA dehydrogenation activity. To study the electronic effect of Pd/C-TPT and its comparative samples, XPS measurements were used on the near surface region electronic states of Pd for Pd/C-TPT and Pd/C catalysts. Fig. 4 shows the Pd 3d_5/2 peaks shifted to lower binding energy in Pd/C-TPT catalyst than those in Pd/C, suggesting a strong electronic interaction between Pd NPs and C support after incorporation of TPT, leading to the electron transfer and redistribution of Pd. Based on the XPS results, TPT is a strong electron donor and can tune the electronic structure of Pd to form electron-rich Pd NPs. Electron-rich Pd species, with increased electron density in its d-orbitals, lead to strong adsorption of formate, thus pre-dominantly stabilizing the bridging formate species.⁴⁷ Moreover, electron-rich Pd reduces the activation energy required for bond cleavage and facilitates the cleavage of the C–H bond in HCOO*,⁴⁸ allowing for more effective catalytic performance.

Fig. 4 Pd 3d XPS spectra for (1) Pd/C-TPT and (2) Pd/C.

The stability of the Pd/C-TPT catalyst was also investigated by adding the same amount of FA into the reactor after the previous reaction. The result shows that the catalytic performance of the catalyst decreases slightly after four cycles (Fig. S11a†). ICP and XRD results indicate that the metal loading, structure, and crystallinity of Pd/C-TPT are nearly unchanged after the 4th run (Table S1, Fig. S11b†). Moreover, the Pd/C-TPT after the stability test was characterized by TEM, showing that there is just a slight increase in the size after the 4th run (Fig. S11c†), which may cause the slight catalytic activity decay. Furthermore, the reason for the decline in catalytic activities of Pd/C-L and Pd/C-H after cycle testing is also due to the increase in particle sizes (Fig. S12†).

Conclusions

In summary, we have demonstrated a simple but efficient approach for preparing ultrafine and well-dispersed Pd NPs with lattice strain by introducing tripeptide (TPT) anchored on commercial Vulcan XC-72R carbon (Pd/C-TPT). Attributed to the size effect, strain effect and electron effect originating from the strong interaction between the Pd NPs and TPT treated C support, the resultant Pd/C-TPT shows excellent catalytic activity for hydrogen production from additive-free FA dehydrogenation with a high TOF value of 2102 mol H₂ per mol Pd per h at 323 K. The rational design of effective catalysts prepared by a simple and feasible scheme in this work may advance the application of FA as a promising hydrogen source.

Data availability

The authors confirm that the data supporting the findings of this study are available within the article and its ESI.†

Author contributions

Yan Gu: writing the original manuscript. Hongli Wang: methodology and funding acquisition. Yaohao Zhang: carrying out the experiment and data curation. Lu Yang: analyzing the data. Xiaoshan Liu: editing the final version of the manuscript. Xuesong Li: supervision and methodology.

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

This work was supported by the Science and Technology Research Project of the Education Department of Jilin Province (JJKH20230759KJ).

Notes and references

1. L. Guo, K. Zhuge, S. Yan, S. Wang, J. Zhao, S. Wang, P. Qiao, J. Liu, X. Mou, H. Zhu, Z. Zhao, L. Yan, R. Lin and Y. Ding, Nat. Commun., 2023, 14, 7518.
2. S. Kar, M. Rauch, G. Leitus, Y. Ben-David and D. Milstein, Nat. Catal., 2021, 4, 193–201.
3. C. Wan, L. Zhou, L. Sun, L. Xu, D. G. Cheng, F. Chen, X. Zhan and Y. Yang, Chem. Eng. J., 2020, 396, 125229.
4. X. Qin, H. Li, S. Xie, K. Li, T. Jiang, X. Y. Ma, K. Jiang, Q. Zhang, O. Terasaki, Z. Wu and W. B. Cai, ACS Catal., 2020, 10, 3921–3932.
5. M. Liu, Y. Xu, Y. Meng, L. Wang, H. Wang, Y. Huang, N. Onishi, L. Wang, Z. Fan and Y. Himeda, Adv. Energy Mater., 2022, 12, 2200817.
6. X. Qi, K. Obata, Y. Yui, T. Honma, X. Lu, M. Ibe and K. Takanabe, J. Am. Chem. Soc., 2024, 146, 9191–9204.
7. W. Ye, H. Huang, W. Zou, Y. Ge, R. Lu and S. Zhang, ACS Appl. Mater. Interfaces, 2021, 13, 34258–34265.
8. Q. Wang, N. Tsumori, M. Kitta and Q. Xu, ACS Catal., 2018, 8, 12041–12045.
9. Z. Chen, C. A. M. Stein, R. Qu, N. Rockstroh, S. Bartling, J. Weiß, C. Kubis, K. Junge, H. Junge and M. Beller, ACS Catal., 2023, 13, 4835–4841.
10. Z. Li and Q. Xu, Acc. Chem. Res., 2017, 50, 1449–1458.
11. Q. L. Zhu, N. Tsumori and Q. Xu, J. Am. Chem. Soc., 2015, 137, 11743–11748.
12. H. Li, C. Tsai, A. L. Koh, L. Cai, A. W. Contryman, A. H. Fragapane, J. Zhao, H. S. Han, H. C. Manoharan, F. Abild-Pedersen, J. K. Nørskov and X. Zheng, Nat. Mater., 2016, 15, 364–364.
13. J. R. Kitchin, J. K. Nørskov, M. A. Barteau and J. G. Chen, Phys. Rev. Lett., 2004, 93, 156801.
14. P. Moseley and W. A. Curtin, Nano Lett., 2015, 15, 4089–4095.
15. H. Wang, S. Xu, C. Tsai, Y. Li, C. Liu, J. Zhao, Y. Liu, H. Yuan, F. Abild-Pedersen, F. B. Prinz, J. K. Nørskov and Y. Cui, Science, 2016, 354, 1031–1036.
16. J. M. Yan, S. J. Li, S. S. Yi, B. R. Wulan, W. T. Zheng and Q. Jiang, Adv. Mater., 2018, 30, 1703038.
17. L. Bu, N. Zhang, S. Guo, X. Zhang, J. Li, J. Yao, T. Wu, G. Lu, J. Y. Ma, D. Su and X. Huang, Science, 2016, 354, 1410–1414.
18. H. Zhu, G. Gao, M. Du, J. Zhou, K. Wang, W. Wu, X. Chen, Y. Li, P. Ma, W. Dong, F. Duan, M. Chen, G. Wu, J. Wu, H. Yang and S. Guo, Adv. Mater., 2018, 30, 1707301.
19. M. Luo, Z. Zhao, Y. Zhang, Y. Sun, Y. Xing, F. Lv, Y. Yang, X. Zhang, S. Hwang, Y. Qin, J.-Y. Ma, F. Lin, D. Su, G. Lu and S. Guo, Nature, 2019, 574, 81–85.
20. Y. Y. Kim, J. D. Carloni, B. Demarchi, D. Sparks, D. G. Reid, M. E. Kunitake, C. C. Tang, M. J. Duer, C. L. Freeman, B. Pokroy, K. Penkman, J. H. Harding, L. A. Estroff, S. P. Baker and F. C. Meldrum, Nat. Mater., 2016, 15, 903–910.
21. M. Yang and W. J. Song, Nat. Commun., 2019, 10, 5545.
22. D. Murphy and M. N. de Pinho, J. Membr. Sci., 1995, 106, 245–257.
23. S. Davaran, J. Hanaee and A. Khosravi, J. Controlled Release, 1999, 58, 279–287.
24. Q. Huang, L. Zhou, X. Jiang, Y. Zhou, H. Fan and W. Lang, ACS Appl. Mater. Interfaces, 2014, 6, 13502–13509.
25. Y. Kokcu, S. Kecel-Gunduz, Y. Budama-Kilinc, R. Cakir-Koc, B. Bicak, T. Zorlu, A. E. Ozel and S. Akyuz, J. Mol. Struct., 2020, 1200, 127046.
26. L. Lai, L. Chen, D. Zhan, L. Sun, J. Liu, S. H. Lim, C. K. Poh, Z. Shen and J. Lin, Carbon, 2011, 49, 3250–3257.
27. W. Hong, M. Kitta, N. Tsumori, Y. Himeda, T. Autrey and Q. Xu, J. Mater. Chem. A, 2019, 7, 18835–18839.
28. N. Nouruzi, M. Dinari, N. Mokhtari, M. Farajzadeh, B. Gholipour and S. Rostamnia, Mol. Catal., 2020, 493, 111057.
29. L. Li, X. Chen, C. Zhang, G. Zhang and Z. Liu, ACS Omega, 2022, 7, 14944–14951.
30. F. Sanchez, D. Motta, L. Bocelli, S. Albonetti, A. Roldan, C. Hammond, A. Villa and N. Dimitratos, C-J. Carbon Res., 2018, 4, 26.
31. Q. Y. Bi, J. D. Lin, Y. M. Liu, H. Y. He, F. Q. Huang and Y. Cao, Angew. Chem., Int. Ed., 2016, 55, 11849–11853.
32. C. Cui, Y. Tang, M. A. Ziaee, D. Tian and R. Wang, ChemCatChem, 2018, 10, 1431–1437.
33. M. A. Ziaee, H. Zhong, C. Cui and R. Wang, ACS Sustainable Chem. Eng., 2018, 6, 10421–10428.
34. M. Deng, J. Ma, Y. Liu, Y. Pang, C. Yang, T. Cao, Z. Yuan, M. Yao, F. Liu and X. Wang, Fuel, 2023, 333, 126466.
35. Y. Ding, Q. Zhang, L. Zhang, Q. Yao, G. Feng and Z. H. Lu, Chin. Chem. Lett., 2024, 35, 454–458.
36. H. Alamgholiloo, S. Rostamnia, A. Hassankhani, X. Liu, A. Eftekhari, A. Hasanzadeh, K. Zhang, H. Karimi-Maleh, S. Khaksar, R. S. Varma and M. Shokouhimehr, J. Colloid Interface Sci., 2020, 567, 126–135.
37. X. Zhao, P. Dai, D. Xu, Z. Li and Q. Guo, Int. J. Hydrogen Energy, 2020, 45, 30396–30403.
38. L. Zou, Q. Liu, D. Zhu, Y. Huang, Y. Mao, X. Luo and Z. Liang, ACS Appl. Mater. Interfaces, 2022, 14, 17282–17295.
39. K. Jiang, K. Xu, S. Zou and W. B. Cai, J. Am. Chem. Soc., 2014, 136, 4861–4864.
40. S. Du, C. Zhang, P. Jiang and Y. Leng, ACS Appl. Nano Mater., 2019, 2, 7432–7440.
41. M. Yao, W. Liang, H. Chen and X. Zhang, Catal. Lett., 2020, 150, 2377–2384.
42. D. J. Zhu, Y. H. Wen, Q. Xu, Q. L. Zhu and X. T. Wu, Eur. J. Inorg. Chem., 2017, 2017, 4808–4813.
43. S. Zhong, X. Yang, L. Chen, N. Tsumori, N. Taguchi and Q. Xu, ACS Appl. Mater. Interfaces, 2021, 13, 46749–46755.
44. A. Zhang, J. Xia, Q. Yao and Z. H. Lu, Appl. Catal., B, 2022, 309, 121278.
45. X. Sun, G. Zhang, Q. Yao, H. Li, G. Feng and Z. H. Lu, Inorg. Chem., 2022, 61, 18102–18111.
46. A. Bulut, M. Yurderi, Y. Karatas, M. Zahmakiran, H. Kivrak, M. Gulcan and M. Kaya, Appl. Catal., B, 2015, 164, 324–333.
47. X. Cui, W. Li, P. Ryabchuk, K. Junge and M. Beller, Nat. Catal., 2018, 1, 385–397.
48. J. Chaparro-Garnica, M. Navlani-García, D. Salinas-Torres, E. Morallón and D. Cazorla-Amorós, ACS Sustainable Chem. Eng., 2020, 8, 15030–15043.

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Footnote

† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4cy01111b

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