The rational design and fabrication of 2D heterojuctions are proven a promising strategy for boosting the performance of electrocatalysts. Although 2D platinum diselenide (PtSe 2 ) exhibits catalytic activity for hydrogen evolution reaction (HER), the catalytic performance is still unsatisfactory due to its inert basal plane, wide bandgap, and poor electron transfer ability. Herein, a new strategy is reported to construct PtSe 2 /PtCo heterojunctions by partial selenization of PtCo alloy for high-efficiency HER electrocatalyst, which exhibits a low overpotential of 38 mV at the current density of 10 mA cm −2 , a small Tafel slope of 22 mV dec −1 , and a superior stability over 24 h and 1000 cycles. The outstanding HER activity of the catalyst arises from the strong electronic interactions between PtSe 2 and PtCo in the heterojunctions, which induce electron transferring from PtSe 2 to PtCo and the d-band center down shifting, and thus optimize the H * adsorption/desorption. This work provides a novel strategy for constructing highly efficient heterostructure electrocatalysts, which facilitates the applications of hydrogen energy conversion.
Developing high-activity non-noble metal catalysts for improving the ability of water dissociation and H* adsorption/desorption in the hydrogen evolution reaction (HER) process in alkaline and neutral electrolytes is essential but remains challenging. Herein, a Mo-doped NiCoCu alloy with tuned tensile strain and localized electrons is designed and synthesized by combining the solvothermal and annealing methods for achieving ampere-level HER performance. Theoretical calculation results prove that Mo doping induces lattice tensile strain and localized electrons (electrons from Mo to the Ni/Co/Cu atoms), promoting the adsorption of O* and H* from H 2 O molecules on the Mo and Co sites and accelerating water dissociation. Therefore, NiCoCu-Mo 0.078 /CF (CF = copper foam) shows low water dissociation energy, providing sufficient H* during the HER process. Meanwhile, its H* Gibbs free energy value is near zero, implying a rapid H* adsorption/desorption process. Electrochemical results show that NiCoCu-Mo 0.078 /CF achieves better HER intrinsic activity in both a 1.0 m KOH ( η −10 /η −1000 = 35/212 mV) and a 1.0 m phosphate buffer solution ( η −10 /η −1000 = 24/256 mV) compared to NiCoCu-Mo 0 /CF and NiCoCu-Mo 0.163 /CF, and it can continuously operate for 100 h at −1000 mA cm −2 . This work shows a sustainable way to design high-performance catalysts for water electrolysis and proposes a well-performing HER catalyst.
ABSTRACT In order to reduce energy consumption in water electrolysis, it is of great importance to design active and stable electrocatalysts for hydrogen evolution reaction (HER) in alkaline solution, especially based on earth-abundant metal. Here we integrate carbon nanotubes (CNTs) and Ni-Ni(OH) 2 heterostructure multifunctional components to design a self-supported 3D CNTs-Ni-Ni(OH) 2 catalyst for HER by composite deposition and subsequent in-situ oxidation . In alkaline solution, this designed CNTs-Ni-Ni(OH) 2 catalyst exhibits 0 mV onset overpotential, and overpotentials of 65 mV and 109 mV at 10 and 50 mA/cm 2 respectively. Electrochemical measurements, characterizations, and simulation results attribute the outstanding performance to the incorporation of CNTs and heterostructure . CNTs induce the formation 3D catalytic surface, enhance electrochemical active surface area , and more importantly weaken the adsorption of H. Moreover, the formation of heterostructure, especially reversible Ni(OH) 2 , supplies active sites and adjusts the adsorption strength of H atom to an optimal value. CNTs and heterostructure synergistically facilitate water adsorption, promote water dissociation, and accelerate H 2 desorption. Significantly, integration of multifunctional components supplies a distinct strategy for development of cost-effective electrocatalyst with outstanding performance.
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