Host–Guest\nStructure Enabling Electrocatalytic\nHydrogen Evolution Performance by POM@TM-BDC Composites

Developing\neconomical, efficient, and earth-rich electrocatalysts\nfor hydrogen evolution reaction (HER) is quite challenging and ideal.\nWe propose that [P<sub>2</sub>W<sub>18</sub>O<sub>62</sub>]<sup>6–</sup> as the guest, due to its excellent reversible 18 electron-transfer\ncapacity and redox properties, and then TM-BDC (TM = Ni, Co, Fe, BDC\n= 1,4-benzene-dicarboxylate) as the host make [P<sub>2</sub>W<sub>18</sub>O<sub>62</sub>]<sup>6–</sup> packaged and not escape\ndue to its porous structure. Benefiting from strong redox-competent\ninteractions between [P<sub>2</sub>W<sub>18</sub>O<sub>62</sub>]<sup>6–</sup> and porous structures of TM-BDC and full exposure\nof abundant active sites, three {P<sub>2</sub>W<sub>18</sub>}@TM-BDC\ncomposites exhibited excellent HER activity, with {P<sub>2</sub>W<sub>18</sub>}@Ni-BDC requiring 198 mV (overpotentials) and 104 mV/dec\n(Tafel slope) for HER. More importantly, three {P<sub>2</sub>W<sub>18</sub>}@TM-BDC composites show excellent stability, with the voltage\nremaining nearly constant for 24 h. Meanwhile, the linear sweep voltammetry\n(LSV) and electrochemical impedance spectroscopy (EIS) curves of three\n{P<sub>2</sub>W<sub>18</sub>}@TM-BDC overlap well with the initial\ncurve after the stability test. Our work offers a promising strategy\nfor synthesizing high-performance electrocatalysts and broadens the\nscope of nonprecious metal composite material preparation.