Multilayered Molybdate Microflowers Fabricated by One-Pot Reaction for Efficient Water Splitting

The development of high-performance, low-cost and rapid-production bifunctional electrocatalysts towards overall water splitting still poses huge challenges. Herein, the authors utilize a facile hydrothermal method to synthesize a novel structure of Co-doped ammonium lanthanum molybdate on Ni foams (Co-ALMO@NF) as self-supported electrocatalysts. Owing to large active surfaces, lattice defect and conductive channel for rapid charge transport, Co-ALMO@NF exhibits good electrocatalytic performances which requires only 349/341 mV to achieve a high current density of 600 mA cm^-2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Besides, a low cell voltage of 1.52 V is required to reach the current density of 10 mA cm^-2 in alkaline medium along with an excellent long-term stability for two-electrode configurations. Density functional theory calculations are performed to reveal the reaction mechanism on Co-ALMO@NF, which shows that the Mo site is the most favorable ones for HER, while the introduction of Co is beneficial to reduce the adsorption intensity on the surface of Co-ALMO@NF, thus accelerating OER process. This work highlighted the importance of the structural design for self-supporting electrocatalysts.

Novel Ni2P-microporous nickel phosphite supported on nitrogen-doped graphene composite electrocatalyst for efficient hydrogen evolution reaction

Transition metal phosphides are regarded as promising hydrogen evolution reaction (HER) electrocatalysts for water splitting. An efficient mass-transfer mechanism can be promoted through constructing microporous structures. In addition, introducing carbon materials as carriers to form interface interactions is beneficial for increasing electronic conductivity so as to promote the catalytic activity further. In this work, a nitrogen-doped graphene (NGO)-supported microporous nickel phosphide-nickel phosphite (Ni₂P-Ni₁₁(HPO₃)₈(OH)₆@NGO, Ni₂P-MPH@NGO), where Ni₂P nanoparticles uniformly fill the micropores of Ni₁₁(HPO₃)₈(OH)₆and then are supported on two-dimensional NGO via a simple two-step method, has been studied as a novel efficient electrocatalyst for HER. Compared with carbon nanotubes and graphene as carbon-based carriers, the optimized Ni₂P-MPH@NGO catalyst shows excellent HER performance with a smaller overpotential, lower Tafel slope and long-term catalytic durability under acid conditions. The results demonstrate that NGO can enhance the catalytic activity of Ni₂P-MPH@NGO efficiently. The results show that the synergistic effect of the microporous structure of Ni₁₁(HPO₃)₈(OH)₆and NGO effectively improves the catalytic activity of the Ni₂P-MPH@NGO composite catalyst, which provides a promising strategy for the design of a new low-cost and high-efficiency HER electrocatalysts.

Delicate Control on the Shell Structure of Hollow Spheres Enables Tunable Mass Transport in Water Splitting

In the study of structure-property relationships for rational materials design, hollow multishell structures (HoMSs) have attracted tremendous attention owing to the optimal balance between mass transfer and surface exposure. Considering the shell structure can significantly affect the properties of HoMSs, in this paper, we provide a novel one-step strategy to continually regulate the shell structures of HoMSs. Through a simple phosphorization process, we can effectively modify the shell from solid to bubble-like and even duplicate the shells with a narrow spacing. Benefitting from the structure merits, the fabricated CoP HoMSs with close duplicated shells can promote gas release owing to the unbalanced Laplace pressure, while accelerating liquid transfer for enhanced capillary force. It can provide effective channels for water and gas and thus exhibits a superior electrocatalytic performance in the hydrogen and oxygen evolution reaction.

A bimetal hierarchical layer structure MOF grown on Ni foam as a bifunctional catalyst for the OER and HER

The as-synthesized NiFe-MOF-5 exhibited an overpotential of 168 mV at 10 mA cm⁻² for OER and a voltage of 1.57 V at 10 mA cm⁻² for overall water splitting, outperforming most non-noble metal catalysts reported in 1 M KOH.

Interconnected porous nanoflakes of CoMo2S4 as an efficient bifunctional electrocatalyst for overall water electrolysis

Interconnected porous nanoflakes of the bimetallic CoMo₂S₄ are synthesized and investigated as bifunctional catalysts for highly efficient overall water electrolysis.

Performance enhancement of oxygen evolution reaction through incorporating bimetallic electrocatalysts in two-dimensional metal–organic frameworks

We designed and synthesized a series of bimetallic and monometallic 2D metal–organic framework electrocatalysts with excellent stability, discussing their different electrochemical catalysts for oxygen evolution reaction (OER).