A bridging coordination of urea tailoring metal hydroxides oxygen evolution catalysts promotes stable solar water splitting

Hydrothermal-Dependent Oxygen Vacancy-Rich NiFe Layered Double Hydroxide/BiVO4 Photoanodes for Stable Solar Water Splitting

“…Based on this, the linear slope of the ΔJ = J a − J c versus the scan rate (Figure S15c,d) corresponds to twice the C dl , and therefore, the slope value can be utilized to evaluate the relative changes in the ECSA. 24,28 We observe that the slope of v-NiFe-LDH/BiVO 4 is 5.7 times higher than that of the BiVO 4 photoanode, which further demonstrates that v-NiFe-LDH/ BiVO 4 provides more active sites by creating surface O vac 's. Meanwhile, the charge separation efficiencies (η sep ) were obtained in accordance with eq S5.…”

“…Driven by the incentive to lower the cost of photoanodes, some transition-metal oxides or hydroxides, including layered bimetallic hydroxides and other oxides, as OER cocatalysts have been exploited in recent years . Recent studies have showed that layered double hydroxides (LDHs) with their distinctive two-dimensional structure and tunable chemical composition as OER cocatalysts can provide active sites owing to its optimal adsorption energy achieved at the doping sites and then widely facilitate the PEC activity of BiVO 4 when transitional metals (i.e., Ni, Co, Fe, Zn, and Mn) are doped in. − For instance, the synthesis of a NiFeY-LDH cocatalyst deposited upon pure BiVO 4 was reported by He et al, and they demonstrated that the addition of Y modified the chemical environment of Ni and reduced the surface recombination, leading to the establishment of a NiFeY-LDH/BiVO 4 photoanode with high photocurrent density (5.2 mA cm –2 ) and long-term stability (around 25 h) . Yue et al introduced surface defects through plasma treatment to prepare ultrahydrophilic H-CoAl-LDH/BiVO 4 with a photocurrent density of 3.5 mA cm –2 .…”

Directional Charge Transfer Channels in a Monolithically Integrated Electrode for Photoassisted Overall Water Splitting

“…Hydrogen, a carbon-free emission energy carrier, is regarded as an ideal clean fuel to substitute traditional fossil fuels. − Photo/electrocatalytic water splitting provides a green route to produce sustainable hydrogen using two of the most abundant resources on earthwater and sunlight, as well as the renewable electricity generated from them. − Generally, catalysts are required to reduce the overpotential for water splitting that includes two half-reactions, i.e., the two (four)-electron hydrogen (oxygen) evolution reaction (HER (OER)). Photocatalysis uses the photoexcited carriers to trigger the HER/OER (Figure a), , while a suitable voltage is required for electrocatalysis (Figure b). − As a self-driven device, the photoelectrochemical (PEC) system only displays low efficiency due to its small photogenerated voltage (Figure c). − One prevailing scheme to increase the solar-to-hydrogen conversion efficiency is to monolithically integrate a photocatalyst (usually semiconductor material) with electrocatalysts in an electrode (Figure d), in which the former efficiently gathers sunlight and excites carriers, and the latter lowers the overpotential (especially for the OER), mediates the carrier transfer, and provides active sites for the water redox reaction. , However, a typical conundrum in this field is related to the fact that the excellent photocatalyst/electrocatalyst interface cannot be easily achieved via conventional physical combination, resulting in high interface impedance and intrinsic poor charge-carrier separation and mobility of the photoresponse constituent which will inevitably reduce the diffusion efficiency of photogenerated charge carriers from the photocatalyst to the electrocatalyst surface and largely limit its whole efficiency and commercialization. − Therefore, the construction of directional charge transfer channels between the reasonable integrated photo/electrocatalyst to promote interfacial charge transfer is one of the most crucial steps to improve the energy conversion efficiency in photoelectrocatalytic water splitting, but it has remained very challenging to date.…”

Effective regulation on catalytic performance of nickel–iron–vanadium layered double hydroxide for urea oxidationviasulfur incorporation

“…As is known to all, it is well demonstrated that NiFe-based catalysts, relating to the corresponding oxides, (oxy)hydroxides, sulfides, selenides, phosphides, and assorted hybrids, 13–19 have been explored as excellent substituted materials by virtue of their impressive catalytic performance toward the UOR in recent years. In particular, Ni–Fe layered double hydroxide (LDH) has received more research interest in the UOR due to its unique lamellar structure, tunable intercalation spacing and metal composition, and abundant active sites, in addition to the indispensable synergistic effect of Ni and Fe.…”