Search

Herein, a novel supramolecular-confinement pyrolysis strategy was proposed to construct ultrafine Ni-Mo2C nanoparticles uniformly distributed on N,P co-doped carbon (NPC) by using polyoxometalate supramolecular aggregate as precursor. Ni-Mo2C/NPC exhibits remarkable electrocatalytic activity for hydrogen evolution reaction (HER) in both acidic and alkaline conditions, as well as superior long-term durability. Combining EXAFS with DFT calculations, we demonstrate that Ni species were atomically dispersed and anchored by Mo2C lattice and P atoms from NPC, thus defining Mo(C)–Ni–P active sites, which enhance the intrinsic catalytic activity of Mo2C by atomic-scale Ni doping and Ni–P catalyst-substrate chemical coupling. The Mo(C)–Ni–P sites have optimal hydrogen adsorption free energies and can precisely regulate and activate the neighboring C, leading to excellent HER performance. This work developed a “bottom-up” polyoxometalate-based supramolecular approach for in-situ assembly of high-active HER catalytic sites, which will provide opportunities to design and fabricate low-cost and efficient atomic-scale catalysts for clean energy conversion.

Developing catalysts with high activity and high atom utilization as well as exploring catalytic active sites are the biggest challenges for the electrocatalytic hydrodechlorination technology. Herein, a novel strategy of Pd crystal transformation induced by in-situ doping was proposed, and a series of amorphous Pd–P nanoparticles (NPs) with controllable coordination environment were synthesized successfully. The amorphous Pd–P NPs catalyst exhibits the highest activity for electrocatalytic hydrodechlorination and good cycling stability when the Pd–P coordination number is 3 and the Pd–Pd coordination number is 4. The 4-chlorophenol hydrodechlorination efficiency of Pd–P-60 NPs reaches 100 % within 2 h, and the mass activity is 8.58 min−1 g−1, which is 5.57 times as high as that for crystalline Pd NPs catalyst. Theoretical calculation shows that Pd–P catalyst facilitates the desorption of phenol and weakens the toxic effect on active sites. Density of states indicate that the doping of P results in a downshift of d-band center, facilitating the desorption of phenol. This work discovers the crystal effect and coordination effect of amorphous Pd–P NPs for electrocatalytic hydrodechlorination, which lays an important theoretical foundation for the design and development of high-performance Pd-based catalysts for electrocatalytic hydrodechlorination.