Self-Standing Nanoporous NiPd Bimetallic Electrocatalysts with Ultra-Low Pd Loading for Efficient Hydrogen Evolution Reaction

Surfactant-free CuxPty nano-alloys with controllable atomic ratios and their enhanced electrocatalytic activity

The electrocatalytic mechanisms of electrocatalysts were constrained by the disparities between the genuine catalytic interface and construction interface. This work demonstrated the relationship between the CuxPty nano-alloy atomic ratios and their catalytic performance. Firstly, we developed a facile synthesis of surfactant-free CuxPty nano-alloys with tunable Cu atomic ratios (ranging from 35 to 72 at%) under ambient conditions. Considering no surfactant-free was applied, surface active sites were uncovered, which was beneficial to ensured consistency between the calculated interface and the actual interface. Based on the experiment and calculation, the relationship between the Pt loading rate and electrocatalytic activity of CuxPty nano-alloy toward hydrogen evolution reaction (HER) was systematically investigated. Under the acidic media, the over-potential by Cu72Pt28 was 7.17 mV, which was 11.5% by the pure Pt nano-particles (NPs). The lower over-potential could be derived from a favorable d-band center of Cu72Pt28, which accelerated the adsorption and desorption of H+. The correlation between the d-band center and the electrocatalytic activity of CuxPty nano-alloy was investigated. Benefiting from the surfactant-free surface, the CuxPty nano-alloy exhibited a favorable electrocatalytic activity toward methanol detection. With the increase in methanol concentration, the anodic peak for methanol oxidation was linearly increased. The linear relationship endowed the CuxPty nano-alloy with a favorable sensor performance. It is suggested that the CuxPty nano-alloy with a higher Pt atomic ratio showed a wider detection range and the CuxPty nano-alloy with a higher Cu atomic ratio showed an enhanced sensitivity. The superior sensor performances could also be utilized for ethanol detection. This work demonstrated the favorable performance of the surfactant-free CuxPty nano-alloy toward hydrogen generation and alcoholic solution (methanol and ethanol) detection. Considering the experiential results were agreed well with calculation, this work pave the way for designing cost-effective electrocatalysis by optimizing its d band center and maximized active sites.

In situ growth engineering of ultrathin dendritic PdNi nanosheets on nitrogen-doped V2CTx MXenes for efficient hydrogen evolution

Immobilizing metal nanoparticles on a support is crucial for catalysts' stability and spatial distribution. MXenes are promising substrates for in situ growth engineering of various electrocatalysts owing to their merits. A stronger binding capacity can be achieved between the in situ-fabricated catalysts and MXenes compared to a common physical combination. Thus, synergistically utilizing morphology modulation, composition optimization, and the interfacial interaction between metal catalysts and supports will maximize the electrocatalytic activity. However, most reported in situ-formed catalysts on MXenes result in solid 0D nanoparticles and in situ growth of nanoalloy catalysts on MXenes with a precisely controlled morphology is still lacking. Herein, nanodendritic PdNi alloys are in situ grown on nitrogen-doped V2CTx, serving as efficient electrocatalysts toward the hydrogen evolution reaction (HER). Thanks to the synergistic effect of the unique nanodendritic structure of PdNi, the merits of N-TBA-V2CTx nanosheets, and the strong metal-support interaction between the PdNi and the N-TBA-V2CTx support, the in situ-formed Pd58Ni42/N-TBA-V2CTx electrocatalyst shows excellent HER performance with an ultralow overpotential of 44.1 mV to achieve 10 mA cm-2 and a lowest Tafel slope of 39.4 mV dec-1, which outperforms Pd58Ni42/TBA-V2CTx, Pd58Ni42, and Pd/C. Remarkably, the Pd58Ni42/N-TBA-V2CTx catalyst can maintain 92.3% of its initial activity even after 50 h of continuous operation.