A dynamic Ni(OH)2-NiOOH/NiFeP heterojunction enabling high-performance E-upgrading of hydroxymethylfurfural

Rational design of the FeS2/NiS2heterojunction interface structure to enhance the oxygen electrocatalytic performance for zinc–air batteries

“…Numerous studies have pointed out that transition metal suldes/phosphides tend to reconstitute at least on the catalyst surface in the strong oxidizing environment of the OER, producing highly reactive amorphous oxides/hydroxides that become the actual active phase of the OER. [73][74][75] Especially in NiFe composites, some of the Ni sites on the catalyst surface oxidize in situ to form highly oxidized Ni]O or highly reactive NiOOH species as the true active sites for the OER, while Fe acts as a strong Lewis acid to promote the oxidation of neighboring Ni sites. 76,77 However, the interpretation of the reaction sites for the ORR is ambiguous.…”

Interfacial stress induced by the adaptive construction of hydrangea-like heterojunctions based on in situ electrochemical phase reconfiguration for highly efficient oxygen evolution reaction at high current density

“…As shown in Fig. 3a, compared with the fresh NS, the Ni 2p spectrum of NS/NOOH-1 shows new convolution peaks at 856.88 and 874.58 eV corresponding to high-valence Ni 3+ , indicating the partial formation of the NiOOH phase after the first CV cycle, 31,42 which corresponds to the redox peak exhibited by the LSV curve (Fig. S7†).…”

“…The above electrochemical consequences reveal that NS/NOOH-30 can achieve an excellent OER performance with high intrinsic activity, fast kinetics, and long-term stability. To elucidate the origin of the enhanced OER activity of NS/NOOH-30, especially to reveal the pivotal importance of introducing lattice strain into electrochemical phase reconstruction in enhancing the intrinsically OER activity, it is necessary to obtain insight into the typical following four-step OER mechanism of NiOOH catalysts under alkaline conditions: 6,30,35,42 2H 2 O → *OH + *H 2 O + e − *OH + *H 2 O → 2*OH + H + + e − 2*OH → OH* + *O + H + + e − *OH + *O → O 2 (g) + H + + e − where * denotes the exposed Ni ions at the edge of NiOOH. The key intermediates are shown in Fig.…”

Effects of chemical composition and vacant oxygen defects on the performance of Ni(OH)2–Ni0.85Se heterostructure nanowires as supercapacitor electrodes

“…5,6 Recent studies show that transition metal hydroxides and oxides are usually used as electrodes for preparing supercapacitors. 7,8 Due to the small difference between the energy levels of transition metals, there are a variety of oxidation states, which are very beneficial to the electron transfer process. 9 Therefore, redox reactions occur easily on an electrode surface containing transition metals.…”