Platinum is the most efficient catalyst for hydrogen evolution reaction in acidic conditions, but its widespread use has been impeded by scarcity and high cost. Herein, Pt atomic clusters (Pt ACs) containing Pt-O-Pt units were prepared using Co/N co-doped carbon (CoNC) as support. Pt ACs are anchored to single Co atoms on CoNC by forming strong interactions. Pt-ACs/CoNC exhibits only 24 mV overpotential at 10 mA cm−2 and a high mass activity of 28.6 A mg−1 at 50 mV, which is more than 6 times higher than commercial Pt/C with any Pt loadings. Spectroscopic measurements and computational modeling reveal the enhanced hydrogen generation activity attributes to the charge redistribution between Pt and O atoms in Pt-O-Pt units, making Pt atoms the main active sites and O linkers the assistants, thus optimizing the proton adsorption and hydrogen desorption. This work opens an avenue to fabricate noble-metal-based ACs stabilized by single-atom catalysts with desired properties for electrocatalysis.
A considerable amount of platinum (Pt) is required to ensure an adequate rate for the oxygen reduction reaction (ORR) in fuel cells and metal‐air batteries. Thus, the implementation of atomic Pt catalysts holds promise for minimizing the Pt content. In this contribution, atomic Pt sites with nitrogen (N) and phosphorus (P) co‐coordination on a carbon matrix (PtNPC) are conceptually predicted and experimentally developed to alter the d‐band center of Pt, thereby promoting the intrinsic ORR activity. PtNPC with a record‐low Pt content (≈0.026 wt %) consequently shows a benchmark‐comparable activity for ORR with an onset of 1.0 VRHE and half‐wave potential of 0.85 VRHE. It also features a high stability in 15 000‐cycle tests and a superior turnover frequency of 6.80 s−1 at 0.9 VRHE. Damjanovic kinetics analysis reveals a tuned ORR kinetics of PtNPC from a mixed 2/4‐electron to a predominately 4‐electron route. It is discovered that coordinated P species significantly shifts d‐band center of Pt atoms, accounting for the exceptional performance of PtNPC.
Identification
of active sites for highly efficient catalysts at
the atomic scale for water splitting is still a great challenge. Herein,
we fabricate ultrathin nickel-incorporated cobalt phosphide porous
nanosheets (Ni-CoP) featuring an atomic heterometallic site (NiCo16–x
P6) via a boron-assisted
method. The presence of boron induces a release-and-oxidation mechanism,
resulting in the gradual exfoliation of hydroxide nanosheets. After
a subsequent phosphorization process, the resultant Ni-CoP nanosheets
are implanted with unsaturated atomic heterometallic NiCo16–x
P6 sites (with Co vacancies) for alkaline
hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).
The optimized Ni-CoP exhibits a low overpotential of 88 and 290 mV
at 10 mA cm–2 for alkaline HER and OER, respectively.
This can be attributed to reduced free energy barriers, owing to the
direct influence of center Ni atoms to the adjacent Co/P atoms in
NiCo16–x
P6 sites. These
provide fundamental insights on the correlation between atomic structures
and catalytic activity.
Ammonia is an industrially relevant chemical that can be directly synthesized from water and air using renewable energy through the electrochemical nitrogen reduction reaction (NRR). However, because of the inert nature of nitrogen, current attempts at synthesizing ammonia under aqueous conditions result in low selectivity and yield rates. The poor electrocatalytic performance is mainly attributed to competing hydrogen evolution, underexposed active sites, inadequate electrode contact, and poor stabilization/ destabilization of key reaction intermediates. Herein, we present a catalyst composed of MoO 2 with surface vacancies dispersed over conductive carbon nanowires that mitigates these obstacles for NRR by providing a high surface area with stable catalytic sites and an underlying conductive support, where a variety of X-ray spectroscopy techniques are used to characterize the MoO 2 catalyst. This uniquely engineered catalyst exhibits exceptional Faradaic efficiencies of over 30% and yields of 21.2 μg h −1 mg −1 at a low potential of −0.1 V vs RHE under ambient aqueous conditions.
Organic-inorganic hybrid perovskite materials have attracted great attention for their great application potential in photovoltaics and optoelectronics. Among them, some 2D and 1D lead-iodide-based perovskites were found to exist room...
Single-atom catalysts (SACs) have shown potential for
achieving
an efficient electrochemical CO2 reduction reaction (CO2RR)
despite challenges in their synthesis. Here, Ag2S/Ag nanowires
provide initial anchoring sites for Cu SACs (Cu/Ag2S/Ag),
then Cu/Ag(S) was synthesized by an electrochemical treatment resulting
in complete sulfur removal, i.e., Cu SACs on a defective Ag surface.
The CO2RR Faradaic efficiency (FECO2RR) of Cu/Ag(S) reaches
93.0% at a CO2RR partial current density (j
CO2RR) of 2.9 mA/cm2 under −1.0 V vs RHE, which outperforms
sulfur-removed Ag2S/Ag without Cu SACs (Ag(S), 78.5% FECO2RR with 1.8 mA/cm2
j
CO2RR). At −1.4 V vs RHE, both FECO2RR and j
CO2RR over Cu/Ag(S) reached 78.6% and 6.1 mA/cm2, which tripled those over Ag(S), respectively. As revealed by in situ and ex situ characterizations together
with theoretical calculations, the interacted Cu SACs and their neighboring
defective Ag surface increase microstrain and downshift the d-band
center of Cu/Ag(S), thus lowering the energy barrier by ∼0.5
eV for *CO formation, which accounts for the improved CO2RR activity
and selectivity toward related products such as CO and C2+ products.
Inorganic perovskite CsPbBr3 is a material used for fabricating highly efficient and stable perovskite solar cells. In this work, a two-step infiltration-spinning method is proposed to obtain CsPbBr3 films with pure phase. Phase transformations between CsPb2Br5, CsPbBr3 and Cs4PbBr6 are investigated by controlling the contact time between the CsBr solution and the PbBr2 substrate. CsPbBr3 films with large grain sizes are obtained after high temperature post-treatment. The CsPbBr3-based solar cells show a high efficiency (approximately 7%) with a short-circuit current density of 6.68 mA cm−2, an open-circuit voltage of 1.47 V and a fill factor of 70.9% under standard solar illumination.
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