Highly dispersed ultra-fine Ru nanoparticles anchored on nitrogen-doped carbon sheets for efficient hydrogen evolution reaction with a low overpotential

Convenient Synthesis of a Ru Catalyst Containing Single Atoms and Nanoparticles on Nitrogen-Doped Carbon with Superior Hydrogen Evolution Reaction Activity in a Wide pH Range

“…With the increase of the reduction temperature, the peak position of Ru 3d 5/2 in Ru/meso-NC- t °C decreased gradually, indicating that the reduction degree of Ru in the Ru/meso-NC- t °C catalysts increased with the increase of temperature (see Table S3 for detailed data). In addition, the energy of Ru 3d 5/2 species in Ru/meso-NC- t °C catalysts are slightly higher than that of the reported 3d 5/2 of Ru(0), which is considered to be due to Ru–N coordination. , The high-resolution N 1s spectra of the Ru/meso-NC- t °C catalysts (as shown in Figure c and see Table S4 for detailed data) can be deconvoluted into four individual peaks assigned to pyridinic-N (398.4 eV), pyrrolic-N (399.6 and 400.6 eV), and graphitic-N (401.6 eV), respectively. , Two pyrrolic-N binding energies are observed, and this is the energy shift phenomenon that may result from the interaction between some pyrrolic-N and metal atoms. , The variation of pyrrole nitrogen content in different valence states with the increase of temperature may be due to the binding strength between ruthenium species and nitrogen species. In addition, it can be found that the content of pyridinic-N decreases and the content of graphitic-N increases with the increase of reduction temperature, and this is similar to the reported work on RuC x N x .…”

“…Comparing LSV curves before and after 20 h CP in Figure f, it was found that the potential required to reach a current density of 10 mA/cm 2 increased by 7 mV (from −15.6 to −26.6 mV vs RHE), while the potential required to reach 100 mA/cm 2 increased by 37 mV (from −124.6 to −161.6 mV vs RHE). It is worth mentioning that the LSV results after long CP tests are rarely reported. ,,,, Under alkaline media, many Ru-based catalysts modified on GCEs show performance degradation after a long time of HER stability test, while the situation is completely different on self-supported electrodes. ,,,,, The slight deactivation of the catalyst may be caused by the partial oxidation of Ru nanoparticles because of the strong adsorption between Ru nanoparticles and the hydroxyl groups (*OH) produced in the process of the HER. In addition, the instability of the Nafion membrane under alkaline conditions may also be another reason for the decline of catalyst activity. , Specially, when the mass loading of catalyst modification on the electrode surface is low, the performance test results will be greatly affected by catalyst detachment.…”

“…The HRTEM images (Figures 1c and S2) of the Ru/meso-NC-t °C catalysts show a lattice spacing of about 0.215 nm, which can be attributed to the Ru(101) crystal plane. HRTEM images also revealed a large number of defects on the carbon substrate in the Ru/meso-NC-t °C catalysts due to the doping of nitrogen, 21 which is conducive to uniform loading of Ru nanoparticles. According to the reported studies, as the temperature is increased, the crystallinity of Ru nanoparticles in the catalyst should also gradually increase, 13,36 but it is very difficult to determine by HRTEM.…”

“…15,39 The high-resolution N 1s spectra of the Ru/meso-NC-t °C catalysts (as shown in Figure 2c and see Table S4 for detailed data) can be deconvoluted into four individual peaks assigned to pyridinic-N (398.4 eV), pyrrolic-N (399.6 and 400.6 eV), and graphitic-N (401.6 eV), respectively. 21,40 Two pyrrolic-N binding energies are observed, and this is the energy shift phenomenon that may result from the interaction between some pyrrolic-N and metal atoms. 5,41 The variation of pyrrole nitrogen content in different valence states with the increase of temperature may be due to the binding strength between ruthenium species and nitrogen species.…”

“…The water splitting is an efficient and clean approach to develop hydrogen energy, especially using the electricity generated by renewable energy. − The recognized catalyst used to produce hydrogen efficiently through water splitting is the expensive and scarce Pt, − which shows the best hydrogen evolution reaction (HER) performance for the most appropriate metal–H bond strength according to the typical Sabatier principle . However, this principle alone cannot explain the phenomenon that the HER activity of Pt under alkaline media is 2–3 orders of magnitude worse than that under acidic media. ,, It is suggested that the energy barrier of water dissociation under alkaline media is the key factor restricting the catalyst’s HER activity. ,− The recent studies show that ruthenium (Ru), which costs only about one-third of the price of Pt, shows superb HER activity under acidic or alkaline media. ,− Thanks to the water dissociation and *OH chemisorption capacity, many Ru-based catalysts show better HER performance than Pt under alkaline media. ,,− …”