Developing non-noble metal-based electrocatalyst with high catalytic activity is essential for advancing hydrogen energy technologies. This study introduces a hydrothermal method for synthesizing order Ni(OH)₂ nanosheets, with H₃O₄₀PW₁₂ (denoted as PW₁₂) loaded onto reduced graphene oxide (rGO) coated on nickel foam (referred to as PW₁₂-Ni(OH)₂/rGO). This method contrasts with the electrodeposition of Ni(OH)₂, where PW₁₂ is added to the synthetic system to direct the assembly and morphology of the Ni(OH)₂ through a hydrothermal reaction. In this work, the nickel foam acts dual roles as both the substrate and the source of nickel for the formation of Ni(OH)₂. The PW₁₂-Ni(OH)₂/rGO nanosheets, when successfully prepared and loaded onto the nickel foam (NF), exhibited superior electrocatalytic activity for the hydrogen evolution reaction (HER) in an alkaline electrolyte, achieving a current density of 10 mA·cm⁻² at an overpotential of 69 mV. Furthermore, we endeavored to expand the application of this material towards the oxygen evolution reaction (OER) by preparing PW₁₂-(Fe/Co)Ni(OH)₂/rGO through the addition of metal cations. This nanocomposite displayed outstanding electrocatalytic activity in alkaline electrolytes, with a current density of 10 mA·cm⁻² at an overpotential of 211 mV, and demonstrated excellent stability over a 50 h period in a 1 M KOH solution. The results presented in this paper offer an effective strategy for the preparation of polyoxometalate-based inorganic materials with diverse functionalities, applicable to both HER and OER.

Polyoxometalates (POMs), renowned for their robust multielectron transfer capabilities, are utilized as photocatalysts. A Cu&POM based complex comprising H₃PMo₁₂O₄₀ (PMo₁₂) and 1,10-phenanthroline has been structured into a supramolecular framework through hydrogen bonding and π–π interactions. This complex demonstrates exceptional photocatalytic efficacy in the oxidation of toluene and the photodegradation of metronidazole. The oxidation of toluene with Cu-PMo₁₂ achieved a yield and selectivity of 100% under low energy conditions, producing unprecedented results and demonstrating outstanding stability in cycling tests. Photodegradation of metronidazole using Cu-PMo₁₂ achieved a degradation rate of 0.178. This work could facilitate the design and synthesis of novel Cu&POM based complexes with superior photocatalytic activities.

Polyoxometalate-based nanocomposites with electrocatalytic activity have been applied in hydrogen evolution reactions (HER). Seawater as the main water resource on the earth should be developed as the water electrolysis to prepare high-purity hydrogen. In this paper, we used two synthesis strategies to prepare the nanocomposite Co₄-POM@Co-PGDY (Co₄-POM: the Kegging-type microcrystals of K₁₀[Co₄(PW₉O₃₄)₂] and Co-PGDY: cobalt-porphyrin linked graphdiyne) with excellent activity for HER. Co-PGDY as the porous material is applied not only as the protection of microcrystals towards the metal ion in seawater but also as the co-electrocatalyst of Co₄-POM. Co₄-POM@Co-PGDY exhibits excellent HER performance in seawater electrolytes with low overpotential and high stability at high density. Moreover, we have observed a key H₃O⁺ intermediate emergence on the surface of nanocomposite during hydrogen evolution process in seawater by Raman synchrotron radiation-based Fourier transform infrared (SR-FTIR). The results in this paper provide an effective strategy for preparing polyoxometalate-based electrocatalysts with high-performance toward hydrogen evolution reaction.