Ni3C-Decorated MAPbI3 as Visible-Light Photocatalyst for H2

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Ni3C Decorated MAPbI3 as Visible-Light Photocatalyst for H2 Evolution from HI Splitting Zhijie Zhao, Jiaojiao Wu, Yan-Zhen Zheng, Nan Li, Xitao Li, and Xia Tao ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.9b01605 • Publication Date (Web): 29 Jul 2019 Downloaded from pubs.acs.org on July 29, 2019

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ACS Catalysis

Ni3C Decorated MAPbI3 as Visible-Light Photocatalyst for H2 Evolution from HI Splitting Zhijie Zhao, † Jiaojiao Wu, † Yan-Zhen Zheng, *, ‡ Nan Li, † Xitao Li, † and Xia Tao *, †, ‡ † State

Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical

Technology, 15 Beisanhuan East Road, Beijing 100029, P. R. China ‡ Research

Center of the Ministry of Education for High Gravity Engineering & Technology,

Beijing University of Chemical Technology, 15 Beisanhuan East Road, Beijing, 100029, P. R. China. *Corresponding author. Tel: +86-10-6445-3680 Fax: +86-10-6443-4784 E-mail: [email protected]; [email protected]

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ABSTRACT A stable composite photocatalyst i.e. MAPbI3 decorated with Ni3C is synthesized by a facile surface charge promoted self-assembly approach, and is demonstrated to be a high-efficiency stable visible-light photocatalyst for H2 evolution in aqueous MAPbI3-saturated HI solution with H3PO2 as a stabilizer. The optimal 15% Ni3C/MAPbI3 suspension under visible illumination displays the HER rate of 2362 μmolg−1h−1, which is approximately 55-fold higher than that of MAPbI3 (43 μmolg−1h−1) and far superior to that of Pt/MAPbI3 (534 μmolg−1h−1). Particularly, the Ni3C/MAPbI3 photocatalyst is ultrastable showing no obvious decrease of HER activity in a given HER process i.e. 10 runs, one-month storage, and another 10 runs. The origin of the superior performance is proven to be predominantly attributed to the improved capabilities of charge carrier transfer/separation as well as the massive reactive centers on the surface of MAPbI3 by Ni3C decoration, together with the high stability of the composite in HI solution during the photoreaction.

KEYWORDS: MAPbI3; Ni3C; photocatalytic H2 production; self-assembly; HI splitting


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1. INTRODUCTION Organic-inorganic hybrid perovskites have shown great potential application as next generation solar cells due to excellent optoelectronic characteristics.1-8 Their success in photovoltaic devices has recently been transferred to generating solar fuels along with instability issue solving in humid conditions by the establishment of dynamic dissolution-precipitation equilibrium of perovskites in saturated hydrohalic acid solutions.9 Perovskites like MAPbI3 have recently been demonstrated to be capable of generating solar fuels via HI splitting reaction, but the achieved hydrogen evolution reaction (HER) rate is vastly inferior to those from conventional semiconductor materials.10-15 Adverse charge recombination of MAPbI3 itself at the nanoscale domain is a huge challenge. To address this issue, Huang et al. reported the composite photocatalyst composed of MAPbI3 and reduced graphene oxide (rGO) exhibiting an outstanding HER activity far higher than MAPbI3 alone for HI splitting, in which rGO acted as an electron acceptor to extract photogenerated electrons.16 Li et al. prepared Pt/TiO2 hybridized MAPbI3 photocatalysts, in which Pt/TiO2 as temporary electron reservoirs facilitated the effective charge transportation and thus enhanced H2 evolution from HI splitting.17 Indeed, examples associated with MAPbI3-based composites for photocatalytic H2 evolution still are scarcely reported so far. Expanding the gallery of MAPbI3based composites with similar or even better photocatalytic activity as well as the scope of the present target reactions still is highly desired and requires more exploration urgently. Ni3C, a fascinating and earth-abundant iron group transition metal carbide, has shown superior electrocatalytic H2 production activity in acidic and/or basic media.18-23 Most recently, Ni3C as cocatalyst has shown to be effective in boosting the photocatalytic HER performance of multicomponent assemblies i.e. Ni3C decorated CdS/g-C3N4 composites, in which Ni3C acts as an electron sink that facilitates prompt charge transportation/separation and surface H2-evolution


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kinetics. 24, 25 Particularly, Ni3C is demonstrated to be better in enhancing the photocatalytic HER rate than the famous noble Pt cocatalyst. These achievements inspire us to assay the possibility of decorating Ni3C onto MAPbI3 for boosting MAPbI3-based photocatalytic HER performance. We herein first report the Ni3C/MAPbI3 composite photocatalytst synthesized by a facile surface charge promoted self-assembly route. We find that the Ni3C/MAPbI3 composites are highly efficient and ultrastable in photocatalytic H2 evolution in MAPbI3-saturated HI solution. The optimal 15% Ni3C/MAPbI3 composite shows the highest visible-light-induced HER rate of 2362 μmolg−1h−1, with a 55-fold enhancement compared with that of MAPbI3 (43 μmolg−1h−1) and far superior to that of Pt/MAPbI3 (534 μmolg−1h−1). Particularly, the Ni3C/MAPbI3 photocatalyst shows no obvious decrease of HER performance in a designed HER process i.e. 10 runs, onemonth storage, and another 10 runs. The outstanding performance may be reasonably explained by the enhanced capability of charge carrier transfer/separation as well as the massive reactive centers on the surface of MAPbI3 by Ni3C decoration, combined with the high stability of the composites themselves in aqueous HI solution under light radiation.

2. EXPERIMENTAL SECTION 2.1. Preparation of Ni3C The Ni3C was synthesized as displayed in Figure S1a. 2 mmol of nickel acetate was added in oleylamine (14 mL) under nitrogen atmosphere. The above solution was heated to 300 °C for 4 hours and then cooled to 25 oC. The obtained precipitates were centrifuged and subsequently rinsed with ethanol, hexane and acetone. Finally, the product was dried in vacuum condition at 60 oC.

2.2. Preparation of MAPbI3 and MAPbI3-saturated HI solution


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The MAPbI3 photocatalyst was synthesized as shown in Figure S1b. The precursor solutions were prepared by dissolving MAI (1 M) and PbI2 in Gamma-butyrolactone (GBL, 10 mL) at 60 oC,

followed by heating to 100 oC for 8 h to grow the crystals. The MAPbI3 precipitates were

obtained by centrifuging with diethyl ether and then drying at 60 oC overnight. MAPbI3 saturated HI solution was obtained via dissolving 1 M of MAPbI3 in 50 mL of HI. This solution was first heated at 70 oC for 0.5 hours, then cooled to 25oC to get the saturated solution MAPbI3 precipitate. The MAPbI3-saturated supernatant solution was preserved for the following experiments. 2.3. Preparation of Ni3C/MAPbI3 The Ni3C/MAPbI3 composites were obtained via an electrostatic adsorption method. Specifically, 50 mg MAPbI3 and several different amounts (2.5, 5, 7.5, 10 mg) of Ni3C were added to MAPbI3-saturated HI solution, respectively. The solutions were heated at 70 oC for 20 min for preheat treatment that allows the complete dissolution of MAPbI3 precipitates, followed by reprecipitation upon cooling. The composite photocatalysts were obtained by electrostatic adsorption of Ni3C on the surface of MAPbI3 during the precipitation-crystallization cycle. For further characterizations, the Ni3C/MAPbI3 composites were finally obtained via centrifuging, rinsing and drying in a vacuum oven set at a temperature of 60 °C for 12 hours. 2.4. Photocatalytic HER Photocatalytic performances of Ni3C/MAPbI3 were assessed using H2 evolution experiments in quartz reactor. 300 mW cm−2 Xe lamp equipped 420nm cut-off filter was adopted as a light source. 10 mL saturated HI solution containing H3PO2 stabilizer and 50 mg photocatalyst was prepared. Before illumination, the suspension was degassed using N2 for 0.5 hours and preheated at 70 oC for 20 min. The generated H2 was measured by Agilent 7890 B GC System. The visible-


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light-driven HI splitting efficiency of Ni3C/MAPbI3 in saturated HI solution without H3PO2 was measured under Xe lamp with a cut-off filter (420 nm). The average intensity of irradiation was set as 100 mW cm −2. The light area was 0.25 cm2. The H+ reduction potential to H2 was 0 V vs. reversible hydrogen electrode (RHE), and the I− oxidation potential to I3− was 0.53 V vs. RHE. The content of HI was 7.58 M. The I3− concentration was estimated as 1.75 × 10−3 M by analyzing the UV-vis absorption spectrum of HI aqueous (Figure S2) and using the related equation9: y = 0.0293x+0.00299 where x is the value of the absorbance at 353 nm, y is the concentration of I3−. The redox potential can be calculated using the Nernst equation. The visible-light-driven HI splitting efficiency was estimated as follows9: E(2H + 2e ― →H2 ) = 0 ― 0.059/2 × log(1/7.582) = 0.052(versus NHE) E(3I ― →I3― + 2e ― ) = 0.53 + 0.059/2 × log(1.75 × 10 ―3/7.583) = 0.371(versus NHE) Based on this, the total potential for HI splitting was calculated as 0.371 V − 0.052 V = 0.319 V. By using this potential, the visible-light-driven HI splitting efficiency could be determined from the following equation9: HI splitting efficiency (%) =

Evolved H2 (mol) × 6.02 × 1023 × 2 × 0.319 (eV) × 1.6 × 10 ―19 Psol (Wcm ―2) × Area (cm2) × time (s)

× 100

The apparent quantum efficiency (AQE) was measured using band-pass filters of 420 nm, 450 nm, 500 nm, 550 nm and 600 nm. The AQE values were estimated as below26: AQE (%) =

2 × number of evolved H2 molecules

number of incident photons

× 100

3. RESULTS AND DISCUSSION 3.1. Structure and morphology of photocatalysts


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The Ni3C/MAPbI3 composite photocatalysts were synthesized via electrostatic selfassembling of positively charged Ni3C (97.2 mV) and negatively charged MAPbI3 (−17.4 mV) in MAPbI3-saturated HI solution (Figure S3).27 The preparation procedure of the Ni3C/MAPbI3 composite is schematically shown in Figure 1 (also see experimental section for details). The crystalline structures of Ni3C and MAPbI3 with loadings of Ni3C were studied by XRD (Figure S4). The XRD pattern of Ni3C exhibits pure hexagonal phase without any other impurity peaks (JCPSD No. 72-1467). The XRD pattern of Ni3C/MAPbI3 shows all characteristic peaks of MAPbI3, and the extra diffraction (113) peak belongs to Ni3C confirming the existence of Ni3C in the composite photocatalyst.28

Figure 1. Schematic diagram of Ni3C/MAPbI3 photocatalysts preparation process. XPS was further adopted to probe the surface compositions and chemical state of the Ni3C/MAPbI3 photocatalyst. As shown in Figure 2a, the XPS spectrum evidences the presence of C, N, I, Pb and Ni elements on Ni3C/MAPbI3. Figure 2b displays the characteristic Ni 2p XPS peaks occurring at 855.4 and 861.5 eV, attributed to the Ni3C phase in Ni3C/MAPbI3.19, 23 It should


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be noticed that the binding energy of Ni 2p in Ni3C/MAPbI3 negatively shifts by ca. 0.2 eV, as compared to pure Ni3C; meanwhile the binding energies of I 3p and Pb 4f in Ni3C/MAPbI3 both positively shift by ca. 0.3 eV compared to pure MAPbI3 (Figure 2b-d). This implies that an electronic interaction does exist between MAPbI3 and Ni3C [29-31], and the partial electrons can transfer from MAPbI3 to Ni3C. The tight adsorption of Ni3C on MAPbI3 facilitates the formation of intimate interfacial contacts, which is highly beneficial for efficient charge-separation/- transfer in the composite photocatalyst. 32 Note that the XPS elemental analysis (Figure S5, Table S1) manifests that the Ni3C loading amounts of Ni3C/MAPbI3 (5%, 10%, 15%, 20%) composites are estimated as 2.5%, 4.2 % 6.3 % and 8.6 %, respectively.

Figure 2. XPS spectra of MAPbI3 and Ni3C/MAPbI3. (a) survey spectrum, (b) Ni 2p, (c) I 3d and (d) Pb 4f. The morphologies and microstructures of Ni3C and Ni3C/MAPbI3 were collected by TEM, HRTEM and SEM. From Figure 3a and the inset, one can observe that the as-prepared Ni3C sample exhibits spherical nanoparticles (NPs) with an average diameter of ~ 48 nm. For the interaction


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between negatively charged MAPbI3 and positively charged Ni3C NPs, MAPbI3 is surrounded uniformly by Ni3C NPs to form a composite structure (Figure 3b), analogous to the central ion and surrounding ligands present in coordination chemistry.33 Since the size of MAPbI3 particles in Ni3C/MAPbI3 composite is much bigger than that of Ni3C NPs, the HRTEM images were captured by focusing in two selected zones, corresponding to Ni3C and MAPbI3, respectively (Figure 3cd). The inter-planar spacings of 0.206 and 0.310 nm are ascribed to the (113) and (220) plane of hexagonal Ni3C and tetragonal MAPbI3, respectively.34,

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Besides, a close contact interface

between Ni3C NPs and MAPbI3 is clearly recognized, which could provide charge carrier transfer/trapping channels and short the transportation length for achieving the photogenerated charges rapid separation, thereby enhancing photocatalytic activity of Ni3C/MAPbI3.24, 36, 37 SEM images (Figure 4a-b) further show that Ni3C NPs are densely attached on the surface of MAPbI3. EDS elemental mapping of Ni3C/MAPbI3 (Figure 4c-f) proves the co-existence of Pb, I and Ni elements in Ni3C/MAPbI3 composite. All above data and analysis results confirm the successful formation of Ni3C/MAPbI3 composite photocatalyst.


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Figure 3. TEM images of (a) Ni3C and (b) Ni3C/MAPbI3. Insert in (a): The size distribution of Ni3C. (c & d) HRTEM images of Ni3C/MAPbI3.

Figure 4. (a & b) SEM images of Ni3C/MAPbI3. The corresponding EDS elemental mapping of Ni3C/MAPbI3 (c-f) at the region shown in (c).


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3.2. Photocatalytic HER activities We performed the photocatalytic HER performance evaluation concerning pure MAPbI3, Pt/MAPbI3 and Ni3C/MAPbI3 with different amounts of Ni3C in saturated HI solution under visible-light (λ ≥ 420 nm) irradiation (Figure 5a). It can be seen that MAPbI3 possesses a very low photocatalytic HER rate of 43 μmolg−1h−1. After anchoring Ni3C on MAPbI3, the photocatalytic HER activities of Ni3C/MAPbI3 composites enhance significantly, and reach an optimum level upon Ni3C loading up to 15%. However, the excess Ni3C loading results in a decline of HER activity, probably ascribed to the sheltering effect of Ni3C.38-40 Remarkably, the highest photocatalytic HER rate of 15% Ni3C/MAPbI3 is 2362 μmolg−1h−1, with a 55-fold enhancement as compared with that of MAPbI3 and farther higher than that of optimized 6 wt.% Pt/MAPbI3 (534 μmolg−1h−1) (Figure S6). The AQE values (Figure 5b) for 15% Ni3C/MAPbI3 at 420, 450, 500, 550, 600 and 800 nm were determined as 16.6%, 16.5%, 14.3%, 12.9%, 11.6% and 1.88% respectively. The variation trends of AQE show an accordant relationship with absorption spectrum of pure MAPbI3, which indicates the H2 production primarily induced by the photocatalysis of MAPbI3.41 Such similar phenomena are also observed in other CdS-based and gC3N4-based photocatalytic systems.24, 25 Additionally, 15% Ni3C/MAPbI3 achieved a HI splitting efficiency of 0.91% under visible illumination (  420 nm) (Figure S7).


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Figure 5. (a) Photocatalytic HER performance under visible-light illumination (λ ≥ 420 nm). (b) Wavelength dependence of the apparent quantum efficiencies for 15% Ni3C/MAPbI3. (c) Cycling photocatalytic HER performance over 15% Ni3C/MAPbI3. The stability of 15% Ni3C/MAPbI3 composite photocatalyst was measured by cycling H2 evolution experiment. The results are displayed in Figure 5c. Ni3C/MAPbI3 shows no obvious decrease of HER activity in a designed photoreaction process i.e. 10 recycles, one-month storage, and additional 10 recycles. Further, the structure, chemical state and morphology of Ni3C/MAPbI3 prior to and after photocatalytic reaction were also examined by XRD, XPS, TEM and SEM (Figure S8-10), showing no phase change and/or structural damage. Such excellent stability of Ni3C/MAPbI3 in MAPbI3-saturated HI solution may be originating from the establishment of dynamic equilibrium between MAPbI3 suspended powders and HI solution that allows restore the surface of MAPbI3 constantly for the continuing oxidation of I- to I3-. Additionally, Ni3C as H2


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evolution active sites is highly stable in HI solution, due to its inherently outstanding acid-proof capability. The comparative data with other groups for photocatalytic HER performance mediated by HI acid are listed in Table S2. 3.3. Origin of photocatalytic performance enhancement To seek for the origin of performance improvement of Ni3C/MAPbI3 photocatalyst, its optical/optoelectric features affecting photocatalytic HER were measured and analyzed in detail. The light absorption capability of Ni3C, MAPbI3 and Ni3C/ MAPbI3 composite were studied by the UV-vis absorption spectra (Figure S11). The absorption spectrum of pure Ni3C shows no apparent absorption edge in visible-light range from 400 to 900 nm, implying the metallic nature of Ni3C.42, 43 MAPbI3 shows a large light absorbance in the full visible region. After loading Ni3C on the surface of MAPbI3, Ni3C/MAPbI3 composite exhibits enlarged particles size. Such enhanced particles size might give rise to light scattering enhancement effect, and finally resulting in additional absorption increase in the visible region.44

Figure 6. (a) PL and (b) time-resolved PL spectra based on Ni3C/MAPbI3 and MAPbI3.

PL emission spectrum is regarded as a useful tool to detect the radiative recombination process of photo-excited charge transfer in photocatalyst.45-47 As displayed in Figure 6a, pure


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MAPbI3 has a strong emission peak due to its high electron-hole recombination. Upon anchoring Ni3C onto the surface of MAPbI3, the emission peak of Ni3C/MAPbI3 almost disappears, mainly due to effective electron transfer from MAPbI3 to Ni3C.27,31,32,46,48-50 Apparently, Ni3C takes positive effects on photo-generated charge separation and transfer, facilitating photocatalytic HER activity. To obtain the details about the decay behavior of photo-generated carriers of photocatalysts, time resolved PL spectra were tested and shown in Figure 6b and Table S3. The PL lifetime of photocatalysts was calculated according to the exponential fitting equation as below:

{ } t

{ } t

Fit = A + B1exp - τ1 + B2exp - τ2

where A, B1, B2, are constants and obtained after fitting every decay curve. τ1 and τ2 reflect the decay components owing to bimolecular recombination and free carrier recombination, respectively.50 According to the fitting results, one can see that the emission lifetimes of Ni3C/MAPbI3 (τ1 = 21.1 ns, τ2 = 71.6 ns) are much shorter than those of MAPbI3 (τ1 = 41.5 ns, τ2 = 165.8 ns). On account of the above decay fitting data, the average PL lifetime (τavg) can be calculated by following equation51: τavg =

B1τ21 + B2τ22 B1τ1 + B2τ2

τavg reflects the overall emission decay behavior of photocatalysts. As a result, Ni3C/MAPbI3 shows a much lower τavg (65.2 ns) than that of pure MAPbI3 (162.5 ns), and this means efficient electron transfer from MAPbI3 to Ni3C and electron-hole separation consequences beneficial to the photocatalytic HER activity.17,52


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Figure 7. (a) Transient photocurrent response, (b) EIS as well as (c) I-V curves based on Ni3C/MAPbI3 and MAPbI3. To further clarify the origin of enhanced HER activity of photocatalyst, opto-electric performance of photocatalysts associated with photogenerated charge separation/transfer were characterized and analyzed by transient photocurrent responses, EIS and the photocurrent densityvoltage measurements. Figure 7a exhibits the chopped photocurrent curves of pure MAPbI3 and Ni3C/MAPbI3 photoelectrodes recorded at the open-circuit potential. In each on-off cycle, the transient photocurrent slope originated from charge diffusion can be observed.53 Ni3C/MAPbI3 produces a photocurrent of ~1.25 μA, 2-fold larger than that of MAPbI3 (~0.62 μA), implying that the photo-excited charge carrier separation between MAPbI3 and Ni3C is largely promoted. 27,31,32, 46,50,54

Furthermore, the photogenerated charge transfer was confirmed by the EIS, as shown in

Figure 7b. The arc radius in the EIS spectra reflects the interface layer resistance, and may be fitted


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by a Randles equivalent circuit (inset in Figure 7b).55 Obviously, Ni3C/MAPbI3 composites show a significantly decreased Nyquist plots diameter compared with pure MAPbI3, revealing an improvement in the electronic conductivity for fast charge transfer across Ni3C/MAPbI3 interface. 27,30-32,46,50,56

Apart from the charge separation and transfer, the catalytic redox reactions on the

catalyst surface play a pivotal role in HER process. Figure 7c shows the HER polarization curves, in which Ni3C/MAPbI3 composite shows a decreased overpotential and an increased cathodic current density as compared with pure MAPbI3, confirming that loading Ni3C on MAPbI3 can efficiently boost electrocatalytic H2-evolution kinetics.25 To gain insight onto the photocatalytic mechanism of Ni3C/MAPbI3, the work function (WF) of Ni3C was analyzed by KPFM (Figure 8a and Au reference shown in Figure S12) through probing the difference surface potentials (VCPD) between Pt/Ir-coated tip and samples. Through the VCPD of Ni3C (4.37 mV), the WF was calculated as about 4.37 eV. Compared with the hydrogen electrode potential (−4.50 eV), the Fermi level of Ni3C was −0.13 V vs. NHE. The flat band potentials of MAPbI3 was estimated via Mott-Schottky experiment. All curves in Figure 8b show a positive slope within the linear region, suggesting it is an n-type semiconductor.24 The flat-band position of MAPbI3 is calculated as at −0.68 V vs. SCE, corresponding to −0.44 V vs. NHE. The CB potential of n-type semiconductors is ∼ 0.10 V more negative than the flat band potential.57 As such, the CB potential was evaluated as approximately −0.54 V vs. NHE. Additionally, the bandgap energy (Eg) is estimated as 1.54 eV by analyzing UV-vis absorption spectra (Figure S13).58 Accordingly, the valance band potential (EVB) of MAPbI3 is obtained as 1.00 V vs. NHE.57, 59

Based on the aforementioned data, the photocatalytic HER mechanism of the Ni3C/MAPbI3

photocatalyst is proposed (Figure 8c). Upon visible-light irradiation, the photons are readily excited to generate electrons from MAPbI3. Owing to matched Fermi level and inherent electrical


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conductivity of Ni3C, the electrons would then transfer to Ni3C effectively, and react with H+ ions to generate H2.60, 61 Meanwhile, I− ions in HI solution are quickly oxidized to I3― ions by consuming the photo-generated holes, and then I3― ions are reduced by H3PO2 in the photocatalytic process, keeping a stable solution condition.

Figure 8. (a) Surface potential mapping of Ni3C reference. (b) Mott-Schottky (MS) plots of MAPbI3. (c) Schematic band diagram of Ni3C/MAPbI3 for HI splitting photocatalytic reaction.

4. CONCLUSIONS An efficient and stable Ni3C/MAPbI3 photocatalyst has been successfully prepared by electrostatic self-assembling of positively charged Ni3C and negatively charged MAPbI3 in


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MAPbI3-saturated HI solution with H3PO2 as a stabilizer. The optimal 15% Ni3C/MAPbI3 composite shows a superior visible-light photocatalytic HER rate of 2362 μmolg−1h−1, with a 55fold improvement as compared with that of MAPbI3 and far superior to that of Pt/MAPbI3. More importantly, the Ni3C/MAPbI3 photocatalyst shows no obvious decrease of HER activity during the whole HER cycling process. The superior photocatalytic HER activity and ultrastability of Ni3C/MAPbI3 is believed to be originating from the improved capabilities of carrier transfer/separation and the massive reactive centers on the surface of MAPbI3 by Ni3C decoration, together with the inherent stability of the composite photocatalyst in HI solution with and/or with no light. This work offers an unusual mode to modify hybrid perovskites by decorating noblemetal-free cocatalyst for enhancing photocatalytic performances.

ASSOCIATED CONTENT Supporting Information Materials characterization, photoelectrochemical measurements, schematic diagram of Ni3C and MAPbI3 formation process, UV-vis light absorption spectrum of the HI aqueous solution, Zeta potentials of MAPbI3 and Ni3C, XRD, XPS, TEM and SEM of Ni3C, Ni3C/MAPbI3 before and after light illumination up to 200 h, XPS survey spectra and elemental analysis data of 5%, 10%, 15% and 20% Ni3C/MAPbI3, surface potential mapping of Au, Eg of MAPbI3. Tables show fit results of the TR-PL spectra and comparison of HER performancebased on photocatalysts reported in literatures and this work. This material is available free of charge via the Internet at http://pubs.acs.org.


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AUTHOR INFORMATION Corresponding Author *Tel: +86-10-6445-3680. Fax: +86-10-6443-4784. E-mail: [email protected]; [email protected] Notes The authors declare no competing financial interest.

ACKNOWLEDGEMENTS We appreciate the financial support from National Natural Science Foundation of China (Nos. 21476019, 21676017).

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Table of Contents Graphic


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Ni3C-Decorated MAPbI3 as Visible-Light Photocatalyst for H2

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