Unconventional direct synthesis of Ni₃N/Ni with N-vacancies for efficient and stable hydrogen evolution
Date
2022
Authors
Zhang, D.
Li, H.
Riaz, A.
Sharma, A.
Liang, W.
Wang, Y.
Chen, H.
Vora, K.
Yan, D.
Su, Z.
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Journal article
Citation
Energy and Environmental Science, 2022; 15(1):185-195
Statement of Responsibility
Doudou Zhang, Haobo Li, Asim Riaz, Astha Sharma, Wensheng Liang, Yuan Wang, Hongjun Chen, Kaushal Vora, Di Yan, Zhen Su, Antonio Tricoli, Chuan Zhao, Fiona J. Beck, Karsten Reuter, Kylie Catchpole and Siva Karuturi
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Abstract
Transition metal nitrides are a fascinating class of catalyst materials due to their superior catalytic activity, low electrical resistance, good corrosion resistance and earth abundance; however, their conventional synthesis relies on high-temperature nitridation processes in hazardous environments. Here, we report a direct synthesis of Ni3N/Ni enriched with N-vacancies using one-step magnetron sputtering. The surface state of Ni3N(001) with 75% N-vacancies is hydrogen-terminated and exhibits four inequivalent Ni3-hollow sites. This leads to stronger H* binding compared to Ni(111), and is affirmed as the most stable surface termination under the electrochemical working conditions (pH ≈ 13.8 and E = −0.1 V) from the Pourbaix diagram. The Ni3N/Ni catalyst shows low crystallinity and good wettability and exhibits a low overpotential of 89 mV vs. RHE at 10 mA cm−2 in 1.0 M KOH with excellent stability over 3 days. This performance closely matches that of the Pt catalyst synthesized under the same conditions and surpasses that of other reported earth-abundant catalysts on planar substrates. The application of Ni3N/Ni as a cocatalyst on Si photocathodes produces an excellent ABPE of 9.3% and over 50 h stability. Moreover, its feasibility for practical application was confirmed with excellent performance on porous substrates and robustness at high operating currents in zero-gap alkaline electrolysis cells. Our work demonstrates a general approach for the feasible synthesis of other transition metal nitride catalysts for electrochemical and photoelectrochemical energy conversion applications.
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This journal is © The Royal Society of Chemistry 2022