Electrochemistry
Ultrathin porous CoP nanosheets drive HER
Open access · cc by · source: Europe PMC
Phosphidation of Co3O4 yields sub-1.1 nm porous CoP sheets with exposed {200} facets and high HER mass activity.
Study at a glance
- Design
- Other — Ultrathin porous CoP nanosheets for acidic HER with DFT H-adsorption analysis
- N
- Electrocatalysis materials study — no sample N
- Population
- CoP ultrathin porous nanosheet electrodes in 0.5 M H2SO4
- Outcome
- HER overpotential, Tafel slope, and mass activity
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
56 and 131 mV reach 10 and 100 mA cm–2; Tafel slope 44 mV dec–1; mass activity 151 A g–1 at 100 mV; ~100% Faradaic efficiency and 20 h stability. P-terminated (200) is preferred.
Methodology
Authors converted Co3O4 to CoP ultrathin porous nanosheets, measured HER in 0.5 M H2SO4, extracted capacitance/ECSA, and computed H adsorption on CoP(100).
Limitations
Device-scale alkaline or seawater HER is untested; ECSA uses an assumed 40 μF cm–2 specific capacitance.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Ultrathin porous CoP nanosheets are the paper that actually ties impedance-style capacitance to a rate. In 0.5 M H₂SO₄, 56 and 131 mV reach 10 and 100 mA cm⁻²; the Tafel slope is 44 mV dec⁻¹; mass activity is 151 A g⁻¹ at 100 mV, with ~100% Faradaic efficiency and 20 h stability. ECSA uses an assumed 40 μF cm⁻² specific capacitance. P-terminated (200) is preferred computationally. Device-scale alkaline or seawater HER is untested.
Evidence for the claim as stated.
Capacitance-derived ECSA, galvanostatic capacity, and an XPS Ni³⁺ ratio are three different electrochemical claims that students lump as 'impedance showed it was better.' CoP uses 40 μF cm⁻² to normalise HER current (56 mV at 10 mA cm⁻²). Stibnite quotes 455.8 versus 190.1 mA h g⁻¹ after 100 cycles. LDH quotes Ni³⁺/Ni²⁺ 0.39 → 1.32 and 95.9% O₂ FE. Those are not replications of one EIS equivalent circuit.
Evidence for the claim as stated.
Stability means different things, and none is a fitted EIS ageing study in these summaries. CoP claims 20 h HER stability and ~100% FE; stibnite claims 70.8% capacity retention over 100 cycles versus sodium metal; LDH quantifies O₂ for 10 min at 50 mA without an electrolyzer lifetime. A Nyquist plot taken once does not equal those tests.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
Capacitance-derived ECSA, galvanostatic capacity, and an XPS Ni³⁺ ratio are three different electrochemical claims that students lump as 'impedance showed it was better.' CoP uses 40 μF cm⁻² to normalise HER current (56 mV at 10 mA cm⁻²). Stibnite quotes 455.8 versus 190.1 mA h g⁻¹ after 100 cycles. LDH quotes Ni³⁺/Ni²⁺ 0.39 → 1.32 and 95.9% O₂ FE. Those are not replications of one EIS equivalent circuit.
- Supports · Stibnite in carbon sheets stores sodium better
- Supports · NaBH4 raises Ni3+ and speeds NiFe LDH OER
Stability means different things, and none is a fitted EIS ageing study in these summaries. CoP claims 20 h HER stability and ~100% FE; stibnite claims 70.8% capacity retention over 100 cycles versus sodium metal; LDH quantifies O₂ for 10 min at 50 mA without an electrolyzer lifetime. A Nyquist plot taken once does not equal those tests.
- Supports · Stibnite in carbon sheets stores sodium better
- Supports · NaBH4 raises Ni3+ and speeds NiFe LDH OER
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