Efficient heterogeneous catalysts play a very important role in the value-updated green hydrogen production from urea-containing wastewater. Herein, NiSe 2 /MoSe 2 heterostructured catalyst with optimized interfacial electron redistribution and urea adsorption energies via a strong built-in electric field was demonstrated effective for the urea-assisted water splitting reactions. Efficient catalytic performance was found on NiSe 2 /MoSe 2 hybrid microsphere owing to the combined merits such as the unique structure features, the strong synergetic coupling effects, the increased active sites, and the high amount of intrinsic Ni 3+ species. Excellent urea oxidation activity was found to drive 10 mA cm −2 at the potential of 1.33 V when loaded on the glassy carbon electrode, and a cell voltage of 1.47 V was required in the NiSe 2 /MoSe 2 ||Pt/C urea-water electrolyzer to drive 10 mA cm −2 , about 220 mV less than that of water electrolysis, indicating a less energy consumption technique during the electrolysis. The spectroscopic and theoretical analysis revealed the effective synergy of the Ni–Se bond and Mo–Se bond that would be promising for efficient catalyst system construction.
He Zhou,Dezhi Kong,Ningning Chu,Hui Wang,Jie Xu,Ye Wang,Tingting Xu
The development of sustainable energy technologies relies on the exploitation of efficient and durable electrocatalysts for water splitting at high current densities. Our work presents a novel bifunctional catalyst, denoted as NM@NC/CC, which combines the benefits of NiSe 2 -MoSe 2 heterojunctions with nitrogen-enriched porous carbon derived from metal-organic frameworks (MOFs). The integration of these components is designed to harness their combined advantages, which include enhanced electron transfer, improved mass and gas evolution dynamics, and an increased number of catalytically active sites. These features collectively optimize the energetics for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). As a result, the catalyst facilitates rapid kinetics for the overall water-splitting process. The NM@NC/CC demonstrates low overpotentials, requiring only 91 mV for the HER and 280 mV for the OER to reach a current density of 10 mA cm −2 . Even at higher current densities of 100 mA cm −2 for HER and 50 mA cm −2 for OER, the overpotentials are only 159 mV and 350 mV, respectively. Additionally, a two-electrode setup using this catalyst achieves a current density of 10 mA cm −2 with a minimal cell voltage of 1.56 V. The insights gained from this study will contribute to the advancement of electrocatalysts for energy conversion technologies.
The construction of cost-effective electrocatalysts with remarkable activity and durability for the urea oxidation reaction (UOR) is urgently needed to achieve sustainable hydrogen production . Herein, a three-dimensional (3D) nanostructure with uniform NiSe 2 /MoSe 2 Mott-Schottky heterojunction nanoneedle arrays densely grown on carbon cloth was designed and fabricated by a hydrothermal method followed by selenization treatment. In the UOR process, NiSe 2 /MoSe 2 undergoes surface reconstruction into a Mo-NiOOH/NiSe 2 composite structure, and Mo-doping can optimize the adsorption/desorption of UOR intermediates. In the hydrogen evolution reaction (HER) process, the directed electron transfer brought by the Mott-Schottky heterojunction can modulate the electronic structure and optimize the d-band center, thus promoting HER. The well-designed NiSe 2 /MoSe 2 as a bifunctional catalyst for urea-assisted electrolysis can reach 10 mA cm −2 at only 1.44 V with almost no performance degradation for 48 h. This work provides a promising avenue to develop efficient HER/UOR bifunctional catalysts toward urea-assisted water electrolysis.
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