Yuan Ma,Nanpu Cheng,Chunhong Li,Muhammad Aizaz Ud Din,Lan Zhao,Nengcong Pan,Yuhan Lei
The development of low-platinum electrocatalysts with high activity in alkaline media is critical for sustainable and cost-effective hydrogen production. In this study, we report a dual-phase engineering strategy to synthesize Pt-CoSe 2 nanoparticles embedded in nitrogen-doped carbon (Pt-CoSe 2 @NC) via controlled pyrolysis of ZIF-67. The resulting catalyst features hierarchical porosity and a 3D conductive network that confines ultrafine Pt particles and enhances interfacial charge and mass transfer. Strong Pt-CoSe 2 interactions induce electron redistribution, elevating cobalt oxidation states and optimizing hydrogen adsorption energetics. Nitrogen doping and surface-oxygenated Co species further boost performance. The optimized Pt-CoSe 2 @NC catalyst exhibits an overpotential of 37.4 mV at 10 mA cm −2 , a Tafel slope of 60.4 mV dec -1 , and remains over 90 % of its initial current density after 24 h in 1 M KOH. Density functional theory (DFT) calculations reveal a shift in the d -band center of Pt due to Pt-CoSe 2 interface formation, leading to near-thermoneutral hydrogen adsorption energy. This work integrates MOF-derived structural control with electronic interface modulation, offering a generalizable blueprint for designing efficient, low-noble-metal HER catalysts.
The low conductivity and catalytic activity of counter electrode (CE) materials in the electrolyte of dye-sensitized solar cells (DSSCs) has resulted in unprecedented challenges, limiting their development. Herein, a highly efficient CE material was synthesized by uniformly distributing transition metal selenides in a metal–organic framework (MOF, denoted as CoSe2@NC), and then integrating carbon nanotubes, which were finally designed as integrated interconnected nanoreactors (CoSe2@NC-CNTs). Consequently, DSSC with three-dimensional (3D) reticular CoSe2@NC-CNT CE displayed a superior power conversion efficiency (PCE) of 9.25%, exceeding that of Pt CE (7.81%). This outstanding performance is attributed to: (1) the increased specific surface area, which promotes the absorption of the dye and electrolyte, (2) the metal-on-MOF hierarchical structure as a unique crystalline porous material, which optimizes the efficiency of the metal nanoparticles, (3) the doping of heteroatom (N), which provides more defect sites and enhances the catalytic activity, and (4) the porous walls of MOF and internal connected CNTs, which provide sufficient pathways for the fast diffusion of electrons and iodine ions. The present work not only strengthens the understanding of the coupling interaction between porous CoSe2@NC and CNTs, but also offers an extended strategy of structuring further well-defined metal-on-MOF hybrids.
Exploration of counter electrode (CE) catalysts with excellent reduction activity to Sn2− and low charge transfer resistance (Rct) is always a major challenge for the development of quantum dot sensitized solar cells. In this work, coral-like CoSe2 - nitrogen-doped porous carbon hydrides (CoSe2-NC) were successfully prepared by two-step calcination of zeolitic imidazolate framework (ZIF), including carbonization and selenization process. Scanning electron microscopy shows that the CoSe2-NC catalyst presents a coral-like microscopic morphology composed of nanospheres. Electrochemical impedance spectroscopy displays that the CoSe2-NC CE presents a low Rct of 1.04 Ω. The PCE of the QDSSC based CoSe2-NC CE is up to 5.06%，which is 26%, 87% higher than those of CoSe2 and NC CEs. The enhanced photovoltaic performance is attributed to the unique coral-like structure and the synergistic catalytic effect of CoSe2 and NC.
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