Highly dispersed Rh prepared by the in-situ etching-growth strategy for energy-saving hydrogen evolution

Barium-induced lattice expansion of Ni(OH)2: enhancing catalytic urea oxidation activity for energy-saving H2 production

Constructing an environmentally friendly and efficient electrocatalyst holds important and profound significance for energy-efficient hydrogen production. Replacing the oxygen evolution reaction with a lower potential urea oxidation reaction (UOR) may save energy in water electrolysis to produce hydrogen. The UOR is characterized by its high energy barrier, which results in slow reaction kinetics. In this study, we introduced Ba(OH)2 into Ni(OH)2 to form uniform nanosheets. Due to the introduction of Ba2+, the lattice expansion of Ni(OH)2 was triggered, leading to significant improvement in UOR activity. The catalyst achieved a current density of 100 mA cm-2 at only 1.316 V and exhibited remarkable stability over time. Density functional theory (DFT) calculations demonstrate that the Ba-Ni(OH)2 site significantly reduces the energy barrier for urea adsorption, intermediate steps, and desorption. This work provides a novel and environmentally friendly strategy for constructing energy-efficient and highly efficient catalysts through the doping of alkaline earth metals.

P-Induced Permeation of Nickel into WO3 Octahedra to Form a Synergistic Catalyst for Urea Oxidation

Small-molecule induction can lead to the oriented migration of metal elements, which affords functional materials with synergistic components. In this study, phosphating nickel foam (NF)-supported octahedral WO₃ with phosphine affords P-WO₃ /NF electrocatalyst. Ni is found to form Ni-P bonds that migrate from NF to WO₃ under the induction of P, resulting in the complex oxides W_1.3 Ni_0.24 O₄ and Ni₂ P₂ O₇ in the particle interior and nickel phosphide on the octahedral grain surface. The catalytic activity of P-WO₃ /NF in the urea oxidation reaction (UOR) is improved by synergistic action of the components in the synthesized hybrid particles. A current density of 10 mA cm^-2 can be reached at a potential of 1.305 V, the double layer capacitance of the catalyst is significantly increased, and the electron transfer impedance in catalytic UOR is reduced. This work demonstrates that small-molecule induction is suitable for constructing co-catalysts with complex components in a simple protocol, which provides a new route for the design of highly efficient urea oxidation electrocatalysts.