Black phosphorus (BP) nanosheet (NS) is an emerging oxygen evolution reaction (OER) electrocatalyst with both high conductivity and abundant active sites. However, its ultrathin structure suffers instability because of the lone pair electrons exposed at the surface, which badly restricts durability for achieving long‐term OER catalysis. Herein, a facile solvothermal reduction route is designed to fabricate Co/BP NSs hybrid electrocatalyst by in situ growth of cobalt nanoparticles on BP NSs. Notably, electronic structure engineering of Co/BP NSs catalyst is observed by electron migration from BP to Co due to the higher Fermi level of BP than that of Co. Because of the preferential migration of the active lone pairs from the defect of BP NSs, the stability and high hole mobility can be effectively retained. Consequently, Co/BP NSs electrocatalyst exhibits outstanding OER performance, with an overpotential of 310 mV at 10 mA cm−2, and excellent stability in alkaline media, indicating the potential for the alternatives of commercial IrO2. This study provides insightful understanding into engineering electronic structure of BP NSs by fully utilizing defect and provides a new idea to design hybrid electrocatalysts.

Spinel Co3O4, consisting of two mixed valence states, Co2+ and Co3+, has attracted enormous interest as a promising electrocatalyst for oxygen evolution reaction (OER). Proper control on the relative proportion of Co2+/Co3+ in cobalt oxide can greatly tune the electronic structure and further optimize its catalytic performance. Herein, a hybrid coupling Co3O4 with black phosphorus (Co3O4@BP) is designed as an efficient catalyst for OER. Electron migration from BP to Co3O4 is achieved in Co3O4@BP, owing to the higher Fermi level of BP than that of Co3O4. Efficient electron transfer can not only create massive active sites with abundant Co2+ but also remarkably suppress the deterioration of BP. Particularly, the Co3O4@BP catalyst outperforms the pristine Co3O4 by over four times and is even 20 times higher than that of bare BP at a potential of 1.65 V versus reversible hydrogen electrode. Our finding provides insightful understanding for electronic engineering in Co3O4@BP by balancing advantages and utilizing drawbacks of Co3O4 and BP.

Alloy/perovskite composites prepared by exsolution of Fe-based perovskite have attracted wide attention due to their embedded and well-anchored structure, which have broad applications in heterogeneous catalysis and energy conversion. Herein, we use Co-doped lanthanum ferrite as a model to study the effect of doping on the B-site exsolution of Fe-based perovskite. CoFe alloy can be exsolved from La0.9Fe0.9Co0.1O3 (LFCO) after heat treatment at 500 °C in a reduced atmosphere, whereas Fe will not be exsolved from La0.9FeO3 (LFO). Density functional theory calculations revealed that the stability of LFCO decreased after Co is doped into the lanthanum ferrite perovskite lattice and the formation energy of the Co–Fe bond on the surface of LFCO is lower than that of Fe–Fe in LFO, which promises an easier exsolution of CoFe alloy than the pristine Fe cluster. In addition, owing to the strong interaction and charge transfer between the exsolved CoFe alloy and parent perovskite, as well as the longer Fe–O bond after exsolution, the exsolved composite can act as an excellent bifunctional electrocatalyst for oxygen evolution and oxygen reduction reactions. Our work not only reveals the mechanism of the alloy exsolution in Fe-based perovskites but also provides a potential route to prepare the highly efficient electrocatalysts.

A novel zero‐dimensional/two‐dimensional CoP/black phosphorus heterostructure was successfully constructed by in situ growth of CoP nanoparticles on the surface of black phosphorus (BP) nanosheets through a facile solvothermal method. The as‐prepared CoP/BP heterostructure exhibited excellent photocatalytic H2 production activity under visible‐ and near‐infrared‐light irradiation. The hydrogen evolution rate of the CoP/BP heterostructure was 694 μmol h−1 g−1, which is about two times higher than that of the Pt/BP heterostructure. The in situ growth of CoP nanoparticles in black phosphorus nanosheets gives rise to excellent interfacial contact between the light‐harvesting material and the co‐catalysts, promotes fast charge transfer, and reduces charge recombination. Because the CoP nanoparticles are anchored on the surface of the BP nanosheets, agglomeration of the CoP nanoparticles is suppressed, and thus, the high surface area and large number of active sites are effectively maintained.

The introduction of iron into Co3O4 can induce a change in the electronic states of Co3+, which is an effective means to regulate the oxygen evolution reaction activity.