Metallic NiPS₃@NiOOH Core–Shell Heterostructures as Highly Efficient and Stable Electrocatalyst for the Oxygen Evolution Reaction

Abstract

We report metallic NiPS 3 @NiOOH core−shell heterostructures as an efficient and durable electrocatalyst for the oxygen evolution reaction, exhibiting a low onset potential of 1.48 V (vs RHE) and stable performance for over 160 h. The atomically thin NiPS 3 nanosheets are obtained by exfoliation of bulk NiPS 3 in the presence of an ionic surfactant. The OER mechanism was studied by a combination of SECM, in situ Raman spectroscopy, SEM, and XPS measurements, which enabled direct observation of the formation of a NiPS 3 @ NiOOH core−shell heterostructure at the electrode interface. Hence, the active form of the catalyst is represented as NiPS 3 @NiOOH core−shell structure. Moreover, DFT calculations indicate an intrinsic metallic character of the NiPS 3 nanosheets with densities of states (DOS) similar to the bulk material. The high OER activity of the NiPS 3 nanosheets is attributed to a high density of accessible active metallic-edge and defect sites due to structural disorder, a unique NiPS 3 @ NiOOH core−shell heterostructure, where the presence of P and S modulates the surface electronic structure of Ni in NiPS 3 , thus providing excellent conductive pathway for efficient electron-transport to the NiOOH shell. These findings suggest that good size control during liquid exfoliation may be advantageously used for the formation of electrically conductive NiPS 3 @ NiOOH core−shell electrode materials for the electrochemical water oxidation.

An Insight on the Electrocatalytic Mechanistic Study of Pristine Ni MOF (BTC) in Alkaline Medium for Enhanced OER and UOR

“…Enhanced catalytic activity is due to the higher ionic strength of OHÀ ions and associated ionic conductivity dependence which is evidenced from the lower R ct value in the EIS studies shown in Figure S10 in the ESI. [5,35,40,41,68,75,76] To support and study the insightfulness of OER on Ni MOF in alkaline medium it was further examined. Figure S11 and S12 show the summary of these results.…”

Extraction of nickel from NiFe-LDH into Ni2P@NiFe hydroxide as a bifunctional electrocatalyst for efficient overall water splitting

“…Recently, transition-metal phosphides have also been demonstrated as efficient electrocatalysts for HER in an alkaline medium,8h,8i,13 besides their high HER catalytic activity in acidic media 8a,8d,8g,14. In addition, it has been demonstrated that bimetallic phosphide NiCoP displays higher HER activity than monometallic phosphide Ni 2 P, due to its optimized H binding energy of nearly zero (close to that of Pt) on the surface of NiCoP, which is beneficial for the reversible adsorption and desorption of H 13 a .…”

Metall‐Phosphor‐Trichalkogenide (MPCh3): von der Synthese zu aktuellen Energieanwendungen

“…Der Degradationsgrad kann vom verwendeten Medium abhängen. [21,22,37,40,42,43,45,47,65,67,68] In Analogie zur HER hat MPSe 3 -Volumenmaterial ein geringeres Onset-Potential als MPS n ,j edoch sind die Ausbeuten bei weitem nicht konkurrenzfähig,u nd die Stabilitäti st sehr mangelhaft. Die XPS-Untersuchung des BiPS 4 -Materials zeigte eine vollständige ¾nderung seiner Zusammensetzung unter Komplettverlust des P. [21] Die MPSe 3 -Materialien waren in alkalischen Medien weniger stabil als in sauren, wobei FePSe 3 und MnPSe 3 jedoch den anderen Verbindungen überlegen waren und deshalb als die beiden interessantesten Vertreter der untersuchten Reihe gelten (Abbildung 4i,j).…”

“…[22] Wiew eiter oben in Abschnitt 4e rwähnt, bestehen noch weitere Herausforderungen im Zusammenhang mit der OER, der anodischen Halbreaktion der Wasserelektrolyse. [45] Abbildung 5. a) SEM-Bild eines exfolierten NiPS 3 -Nanoblatts. [56] Viele Studien haben gezeigt, dass die aktiven Zentren der OER-Katalysatoren heterogene Reaktionsintermediate sind, und für Übergangsmetallkatalysatoren wurden die Spezies M-OH, M=Ou nd M-OOH detektiert.…”

“…Die OER ist auch eine wichtige Halbreaktion in wiederaufladbaren Metall-Luft-Batterien und Brennstoffzellen. [45] Die ORR-Aktivitätv on MPCh 3 ist noch nicht ausgiebig untersucht worden. [66] Eine schnelle Zersetzung des Materials zu freien Ionen oder das Auslaugen der Elemente kann zu wenig stabilen molekularen Katalysatoren führen, ein häufiges Problem bei der OER.…”