The scalable production of hydrogen could conveniently be realized by alkaline water electrolysis. Currently, the major challenge confronting hydrogen evolution reaction (HER) is lacking inexpensive alternatives to platinum-based electrocatalysts. Here we report a high-efficient and stable electrocatalyst composed of ruthenium and cobalt bimetallic nanoalloy encapsulated in nitrogen-doped graphene layers. The catalysts display remarkable performance with low overpotentials of only 28 and 218 mV at 10 and 100 mA cm−2, respectively, and excellent stability of 10,000 cycles. Ruthenium is the cheapest platinum-group metal and its amount in the catalyst is only 3.58 wt.%, showing the catalyst high activity at a very competitive price. Density functional theory calculations reveal that the introduction of ruthenium atoms into cobalt core can improve the efficiency of electron transfer from alloy core to graphene shell, beneficial for enhancing carbon–hydrogen bond, thereby lowing ΔGH* of HER.

Electrochemical water splitting is considered as the most promising technology for hydrogen production. Considering overall water splitting for practical applications, catalysis of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) should be performed in the same electrolyte, especially in alkaline solutions. However, designing and searching for highly active and inexpensive electrocatalysts for both OER and HER in basic media remain significant challenges. Herein, we report a facile and universal strategy for synthesizing nonprecious transition metals, binary alloys, and ternary alloys encapsulated in graphene layers by direct annealing of metal–organic frameworks. Density functional theory calculations prove that with an increase in the degree of freedom of alloys or a change in the metal proportions in FeCoNi ternary alloys, the electronic structures of materials can also be tuned intentionally by changing the number of transferred electrons between alloys and graphene. The optimal material alloys FeCo and FeCoNi exhibited remarkable catalytic performance for HER and OER in 1.0 M KOH, reaching a current density of 10 mA cm–2 at low overpotentials of 149 mV for HER and 288 mV for OER. In addition, as an overall alkaline water electrolysis, they were comparable to that of the Pt/RuO2 couple, along with long cycling stability.

Graphene, a 2D material consisting of a single layer of sp -hybridized carbon, exhibits inert activity as an electrocatalyst, while the incorporation of heteroatoms (such as N) into the framework can tune its electronic properties. Because of the different electronegativity between N and C atoms, electrons will transfer from C to N in N-doped graphene nanosheets, changing inert C atoms adjacent to the N-dopants into active sites. Notwithstanding the achieved progress, its intrinsic activity in acidic media is still far from Pt/C. Here, a facile annealing strategy is adopted for Ir-doped metal-organic frameworks to synthesize IrCo nanoalloys encapsulated in N-doped graphene layers. The highly active electrocatalyst, with remarkably reduced Ir loading (1.56 wt%), achieves an ultralow Tafel slope of 23 mV dec and an overpotential of only 24 mV at a current density of 10 mA cm in 0.5 m sulfuric acid solution. Such superior performance is even superior to the noble-metal catalyst Pt. Surface structural and computational studies reveal that the superior behavior originates from the decreased ΔG for HER induced by the electrons transferred from the alloy core to the graphene layers, which is beneficial for enhancing CH binding.

The synergistic interplay between Ru and MoO2 contributes to an outstanding Pt-like electrocatalytic behavior towards the hydrogen evolution reaction.

Unique nano heterojunction structures encapsulated in highly nitrogen doped graphene layers were synthesized in situ by one-step annealing of PBAs serve as bi-functional ORR and OER catalysts.

The water electrolysis is of critical importance for sustainable hydrogen production. In this work, a highly efficient and stable PdCo alloy catalyst (PdCo@CN) was synthesized by direct annealing of Pd-doped metal-organic frameworks (MOFs) under N2 atmosphere. In 0.5 M H2SO4 solution, PdCo@CN displays remarkable electrocatalytic performance with overpotential of 80 mV, a Tafel slope of 31 mV dec(-1), and excellent stability of 10 000 cycles. Our studies reveal that noble metal doped MOFs are ideal precursors for preparing highly active alloy electrocatalysts with low content of noble metal.

The hydrogen evolution reaction highly relied on Pt electrocatalysts, with high activity and stability. In the past few years, a host of efforts have been made in the development of novel platinum nanostructures with a low amount of Pt because the scarcity and high price of Pt hinder its practical applications. Here, we report the preparation of PtCoFe@CN electrocatalysts with a remarkably reduced Pt loading amount of 4.60% by annealing Pt-doped metal-organic frameworks (MOFs). The electrocatalyst demonstrated an outstanding performance with only 45 mV overpotential to achieve the 10 mA cm current density, which is quite close to that of the commercial 20% Pt/C catalyst. The enhanced catalytic capability is originated from the modification of the electronic structures of CoFe by alloying with Pt. The results indicate that robust and superstable alloy electrocatalysts which contain a very small amount of noble metal could be prepared by annealing noble metal-doped MOFs.

In this work, we rationally combined novel ICG@HES-OA NPs with PEITC for potent PDT. The combination of ICG@HES-OA NPs and PEITC results in synergistic PDT efficacy.