Multi-interfacial engineering of an interlinked NiP-MoP heterojunction to modulate the electronic structure for efficient overall water splitting

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2023-07, Vol.11 (27), p.1533-1543
• Main Authors: Zhang, Wei, Yan, Haijing, Liu, Yue, Wang, Dongxu, Jiao, Yanqing, Wu, Aiping, Wang, Xiuwen, Wang, Ruihong, Tian, Chungui
• Format: Article
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d3ta01789c

Exploring efficient and cost-efficient bifunctional electrocatalysts is crucial for H 2 production via overall water splitting. Multi-interface engineering is a promising strategy to overcome the intrinsic activity limitation of electrocatalysts by the ensemble effect and electron effect but it is challenging. Herein, we elaborately designed and synthesized a multi-interface-coupled heterojunction composed of Ni 2 P and MoP encapsulated by N-doped carbon (Ni 2 P-MoP@NC), which possesses an adjustable electronic structure based on "d-electron complementation" to achieve effective HER and OER catalysis. A post-synthetic modification strategy anchoring Ni 2+ ions on the phosphomolybdic acid (PMo 12 )-organic supramolecular via the multiple linkages of organic ligands is proposed, which ensures the construction of multiple hetero-interfaces electrocatalyst by means of the natural quasi-interfaces of {PMo 12 -organic ligand-Ni}. The organic ligands also play a crucial role in the size control of Ni 2 P-MoP nanoparticles ( ca. 7 nm). Experimental characterization combined with theoretical calculations reveal that the heterojunction triggers the electron redistribution, thereby facilitating water dissociation and optimizing H* adsorption energy to boost the HER, and balancing the adsorption energies of oxygenated intermediates to lower the thermodynamic barrier for the OER. Consequently, Ni 2 P-MoP@NC exhibits excellent HER and OER activity with low overpotentials of 69 and 249 mV at 10 mA cm −2 in alkaline media. The alkali-electrolyzer assembled by Ni 2 P-MoP@NC requires a low voltage of 1.54 V to achieve 10 mA cm −2 with good durability. This work proposes a new route to design various multi-touch heterojunctions constructed using other early and late transition metals. Multi-interface interlinked, small sized Ni 2 P-MoP heterojunctions were constructed by employing a Ni-post-modification strategy of POM-based organic hybrid via the linkages of an organic ligand, which achieves highly efficient overall water splitting.