Revealing the synergy of Sn insertion in hematite for next‐generation solar water splitting nanoceramics

Abstract

Solar water splitting-driven hydrogen fuel production is very attractive due to positive aspects as higher energy density and a renewable energy source arising from water and sunlight. 1 Despite these remarkable overall strengths, sustainable largescale clean hydrogen production is quite far from being available, in particular by the lack of efficient and economically viable electrodes for photoelectrochemical (PEC) cells. These devices involve two redox electrochemical reactions: hydrogen evolution on the cathode and oxygen evolution on the anode, where one or more photosensitive material can be enforced in the device design. 2 It is worth mentioning that oxygen evolution reaction (OER) is the rate-determining step of the photoelectrochemical water splitting, because of the four-electron reaction mechanism of water oxidation, which

Al excess extends Hall‐Petch relation in nanocrystalline zinc aluminate

“…The positive results in improving hardness by Al enrichment in zinc aluminate could provide a better alternative to the recent usage of rare‐earths and transition metals as dopants to improve the mechanics of nanoceramics 24,53 . In addition to the cost associated with the addition of rare‐earth elements to the system, a further complication with rare‐earth doping in spinel materials is the propensity for the rare‐earth oxide to form a second phase as reported by Hasan et al.…”

“…The positive results in improving hardness by Al enrichment in zinc aluminate could provide a better alternative to the recent usage of rare-earths and transition metals as dopants to improve the mechanics of nanoceramics. 24,53 In addition to the cost associated with the addition of rare-earth elements to the system, a further complication with rare-earth doping in spinel materials is the propensity for the rare-earth oxide to form a second phase as reported by Hasan et al in magnesium aluminate. 28 The spinel structure is known for its ability to accommodate significant deviations from stoichiometry: single phases have been reported in magnesium aluminate for deviations as large as 1.84:…”

Thermodynamic and kinetic analyses of sintering in Al‐doped Y2O3 nanoparticles

“…2 When a dopant is introduced into an oxide system, it can form a solid solution with the host, precipitate as a second phase, or segregate to form interfacial excesses where the dopant remains in the host structure but accumulated at the surface and/or the grain boundary. [5][6][7][8] In the presence of dopant segregation, interfacial energies can be affected, significantly altering sintering driving forces in the system. 9 In Al-doped Y 2 O 3 , due to the large difference between the ionic radii of Al 3+ ions (53.5 pm at 6-fold coordination) and Y 3+ ions (90 pm at 6-fold coordination), the formation of solid solution is thermodynamically unfavorable, which may lead to a significant energy of segregation.…”

“…When a dopant is introduced into an oxide system, it can form a solid solution with the host, precipitate as a second phase, or segregate to form interfacial excesses where the dopant remains in the host structure but accumulated at the surface and/or the grain boundary 5–8 . In the presence of dopant segregation, interfacial energies can be affected, significantly altering sintering driving forces in the system 9 .…”

“…Preceramic polycarbosilane polymers are commonly used as precursors to make ceramic fibers 10,39 and ceramic matrix. [7][8][9]40,41 The chemical and volume changes that accompany ceramization of the polymer during pyrolysis have been documented in several studies. For example, see Refs [39][40][41][42].…”