Modulation of Phosphorene for Optimal Hydrogen Evolution Reaction

Abstract

Economical and highly effective catalysts are crucial to the electrocatalytic hydrogen evolution reaction (HER), and few-layer black phosphorus (phosphorene) is a promising candidate because of the high carrier mobility, large specific surface area, and tunable physicochemical characteristics. However, the HER activity of phosphorene is limited by the weak hydrogen adsorption ability on the basal plane. In this work, optimal active sites are created to modulate the electronic structure of phosphorene to improve the HER activity and the effectiveness is investigated theoretically by density-functional theory calculation and verified experimentally. The edges and defects affect the electronic density of states, and a linear relationship between the HER activity and lowest unoccupied states (εLUS) is discovered. The medium εLUS value corresponds to the suitable hydrogen adsorption strength. Experiments are designed and performed to verify the prediction, and our results show that a smaller phosphorene moiety with more edges and defects exhibits better HER activity and surface doping with metal adatoms improves the catalytic performance. The results suggest that modified phosphorene has large potential in efficient HER and provides a convenient standard to explore ideal electrocatalysts.

Photoelectrochemical Synthesis of Ammonia with Black Phosphorus

“…The lower kinetics barrier of HER make it easier to be occurred at lower potential; [ 1a ] meanwhile, at the large potential, the massively surface absorbed hydrogen gas and protons would exclude nitrogen from the reactive sites. [ 13 ] Regarding PEC NRR of BP, there is also an inverted U‐shape relationship between the potential and ammonia yield rate (Figure 2f). Nonetheless, the synthesis efficiency is better than that of EC NRR at same potential.…”

“…These phenomena suggest the BP electrode is unfavorable to HER, which is consistent with previous reports. [ 13 ] This poor HER catalytic ability is beneficial to the selectivity of NRR. When the LSV is taken in the N 2 atmosphere, the enhanced current density, smaller onset overpotential, and Tafel slope show that nitrogen molecules absorb onto the BP electrode so that EC NRR takes place.…”

“…[ 12 ] Meanwhile, weak hydrogen absorption on bare BP also can suppress the competing hydrogen evolution reaction. [ 13 ] These features suggest that BP is suitable for the nitrogen reduction reaction (NRR) which is the core process in ammonia production. Meanwhile, since BP is a direct bandgap semiconductor with high carrier mobility as well as light absorption spanning a wide range, [ 14 ] it has large potential in light‐assisted catalysis.…”

Recent Advances on Black Phosphorus Based Electrocatalysts for Water‐Splitting

“…the ideal ΔG H* is zero . Density‐functional theory (DFT) calculation showed that the lowest unoccupied state ( ϵ LUS ) value corresponds to the suitable hydrogen adsorption strength, and corresponding experiments verified that doping with metal atoms could help enhancing the HER catalytic performance of BP . Various metals have been doped to BP as new electrocatalysts before the above theoretical calculation and experiments.…”

“…[52] Density-functional theory (DFT) calculation showed that the lowest unoccupied state (ɛ LUS ) value corresponds to the suitable hydrogen adsorption strength, and corresponding experiments verified that doping with metal atoms could help enhancing the HER catalytic performance of BP. [53] Various metals have been doped to BP as new electrocatalysts before the above theoretical calculation and experiments. Cu nanoparticles have been deposited onto the surface of few-layer BP by using an ultrasonication-facilitated method, Cu/few-layer BP performed better HER performance than Cu/ few-layer graphene.…”